More than 3.5 million people, primarily in white-collar jobs on the East and West Coasts, clutch its BlackBerry cell phone/e-mail devices on planes, trains and automobiles.

People become so dependent on being in continuous corporate contact that they call these little machines CrackBerrys. And people spend so much time flailing away at their tiny Tom Thumb keyboards that the American Society of Hand Therapists has issued an alert–this is not a joke–about a painful condition nicknamed BlackBerry Thumb.

Don’t look now, but it’s all about to get worse–or better, depending on your point of view. On Tuesday, RIM unveiled the BlackBerry 8700c, a thoroughly modernized version of a gizmo whose technologies were rock-solid but a tad behind the times. It goes on sale Nov. 21.

BlackBerrians shouldn’t worry. The new version is still very much a BlackBerry. After all, the only components RIM changed were the screen, keyboard, battery, speaker, processor, software and price (now $300, available at first only from Cingular). The headphone jack was left pretty much alone.

Some of the changed features, like the screen, hit you right away. Recent BlackBerry models have color screens, but they’re not backlit. They can go a week on a battery charge, but you can’t use one to read a theater program in the dark. The 8700c, though, has a state-of-the-art, bright, high-resolution screen (240 by 320 pixels). Its ambient light sensor even dims the screen when the room light is low, and turns off the illuminated keys when the room is bright.

Unfortunately, the electricity required has to come from somewhere; the new BlackBerry’s “four hours of talk time” battery doesn’t last nearly as long on a charge as the old one. You’ll have to charge this one every three days or so.

The next most evident change is in the design. Thanks to a new, modernized color scheme, the gadget is not so much a BlackBerry as a GrayBerry. It’s also slightly narrower and shallower than the previous model (4.3 by 2.7 by 0.8 inches), and at 4.7 ounces, so light it practically feels hollow. Still, considering how unlike a cell phone the BlackBerry slab feels pressed to your ear, any design narrow-mindedness is welcome.

Other changes don’t become apparent until you start using the 8700c. A more powerful Intel processor makes the device feel snappier, and a built-in Bluetooth transmitter lets you make calls using a wireless earpiece or in a Bluetooth-equipped car.

The familiar thumb-tappable keys, each about the width of a human tooth, are there, though they’re slightly more crowded because the BlackBerry itself is a tad narrower. But now there’s a dedicated zero key and two “convenience keys” you can program according to your whims.

The newly repositioned microphone offers better phone quality, which, coupled with the new Send, End and Mute keys, makes clear that RIM is finally treating the cell phone function as a first-class citizen instead of an afterthought.

The rest of the 8700c’s goodies are technical tweaks. The phone can now connect to the Internet over Cingular’s Edge network, which is supposed to bring high-speed Web surfing to cell phones. Of course, that’s high-speed compared with other cell phones, not high-speed compared with a cable modem. Even this new BlackBerry, in a major city with a solid Edge connection, can take its sweet time dragging a Web page onto the screen. (Fortunately, you can fill the time by hitting Alt-Esc and temporarily hopping into another program, like your calendar. That new keystroke summons a Mac- or Windows-like row of application-switcher icons.)

The new Enhance command is clever, too. When somebody sends you a photo or PowerPoint presentation, a 320-by-240-pixel rendition downloads quickly. But what if you want to see a portion up close? You can magnify it, but blurrily. With the Enhance command, the BlackBerry fetches more of the original image from the Internet source, making the enlarged view appear crisp and clear. The Enhance command reminds you of those implausible movie scenes where a technician freezes a security camera tape, zooms in on the bad guy, then manages to comply with the detective’s request: “Can you make it any clearer?”

In many other ways, the new BlackBerry works like the old one–for better or worse. You still operate it by turning a clickable thumbwheel on the right edge to highlight on-screen menus and icons–a technique that might sound less efficient than tapping on a touch screen, but lets you do everything one-handed.

The BlackBerry still drips with the creative juices of clever programmers, whose convenient shortcuts take the sting out of using the tiny keyboard. For example, you can capitalize a letter by holding its key down for an extra half-second. When you’re reading a message, tapping T or B scrolls to the top or bottom (and R opens a reply). Even accented letters are easy: Just hold down a letter key and spin the thumbwheel to cycle among variations.

And the BlackBerry still shines at the stunt that put it on the map: receiving e-mail, not every 15 minutes, but in real time, as messages are sent. And if your corporate master has invested in something called a BlackBerry server, then your pocket gadget is an amazing, wireless mirror for the e-mail program on your computer at work. Reply to a message, and you’ll see the reply in your Sent mail folder back at the office.

On the other hand, many of the BlackBerry’s deficiencies are still with the 8700c, too. For example, if you have a regular e-mail account, you don’t enjoy that real-time mirroring effect; if you delete a message on the BlackBerry, you have to delete it again when you return to your computer. There’s still no music player, no built-in camera and no video features whatsoever.

Yes, these limitations reinforce the BlackBerry’s mission as a tool for corporations, not individuals. (You know you’re in corporation-land when the 56-page software license booklet is 75 percent longer than the user’s guide.) But aren’t most corporate workers still human beings? Don’t they enjoy taking pictures and listening to music just like normal people?

Maybe that’s why the BlackBerry’s rival, the Treo 650, has also become wildly popular. It plays music, takes pictures, feels more solid and comfortable in the hand, runs thousands of add-on Palm programs and is available from all major cell phone companies. (The Cingular-only restriction will be an immediate deal breaker for thousands of prospective 8700c buyers.)

There’s also another cause for pause: the dark legal cloud hanging over RIM. Two years ago, a tiny patent-holding company called NTP won a patent-infringement lawsuit against RIM. A court awarded NTP a chunk of cash, plus an injunction prohibiting RIM from selling BlackBerrys in the United States–or even providing BlackBerry service. The ban was suspended while RIM appealed. But RIM also lost that legal round, and an attempt to settle out of court collapsed. All those CrackBerry fanatics fear the nightmare situation of having to go cold turkey when NTP returns to court to reactivate the injunction.

In truth, a BlackBerry blackout isn’t likely; RIM has already announced it has a workaround for the disputed technology. Meanwhile, on the merits of design and features, the 8700c is a welcome development and deserves to be the new standard model. If you can tolerate the shortened battery life and if Cingular has service where you work and play, you’ll find in the new BlackBerry a bright, fast, solid communicator that’s more habit-forming than ever.