I do think it will be based on the iPhone OS rather than Mac OS X, although it could be a completely new variant of OS X that borrows features of both Mac OS X and iPhone OS. The reasons I don't think it will use the Mac OS is that touch handling isn't an integral part of the responder chain. Cocoa Touch is also "cleaner" than Cocoa. By that, I mean there are less legacy libraries so less code that uses design patterns from a different era of programming. And, finally, for reasons that John Gruber talked about on Monday, because Apple has control over the entire OS with the iPhone OS, and Apple likes control.
Breaking: I've heard a rumor that the next version of the iPhone OS will be renamed to something along the lines of iOS, and that the device will use it. The rumor is from a credible source, so I give it a pretty high likelihood, though wouldn't say it's 100%Beyond that, I don't know. Will it use window like OS X, or will every application take over the whole screen like the iPhone OS? My guess is the former. Will it have background processing? I'm betting on some form, but not necessarily full, unfettered daemons like OS X. I'm betting it has standard IO ports such as USB-2 and Mini DisplayPort, and will use a more powerful chip than the iPhone. And those are all safe bets, I know, but I don't profess to be a prophet.
I've seen a number of "pundits" making dire predictions about the tablet being unpopular in business and have even read articles discussing how to keep the things off their networks. FUD. Probably written by bloggers who take money in some form or another from Microsoft. If not, then they're written by people with a complete lack of vision.
I also read this article. It's focused on one industry: Healthcare. But many of the points it makes are relatively universal. I spent many years working in so-called "Enterprise Software" for my day job, writing and implementing complex software in large corporate and government environments. From my experience, the vision in this article is spot on, just stated in terms that are too narrowly focused.
Think of all the specialty computing devices that get carried around on a daily basis. Think of the devices that the UPS drivers, FedEx Drivers, and Postal Carriers all have. Now think of all the jobs where a portable device COULD be used, but aren't. Think of the way the Apple Store employees use iPod Touches to check out customers. If today's announcement delivers on the unspoken promises, the possibilities are quite literally endless. A hotel concierge, for example, could be freed up to do his or her job anywhere in the hotel with a tablet. Maitre's D's could have their reservation information and access to their in-house beeper system under their arm, rather than be tied to a podium. School teachers could walk around their room and take attendance rather than having to sit at his or her desk marking in a gradebook or typing into a regular computer.
One prediction I feel comfortable making: The tablet, like the iPhone, will be a programmable device priced so that even consumers can afford it. Also, the touch screen will mean that its interface can adjust to whatever task needs to get done, not unlike the bridge controls on the U.S.S. Enterprise back in Star Trek:The Next Generation. That means it can be made to do most anything somebody needs it to do.
There are a lot of small and medium-sized businesses out there that can't afford to have a specialty device designed and programmed the way FedEx can, but certainly could afford a couple of consumer-priced tablets and the cost of developing a small, special-purpose piece of software, or to license a piece of niche software. There are a lot of jobs that involve walking around and where even a laptop computer isn't practical, but a touch-based tablet would be. The tablet and the iOS SDK (or whatever it ends up being called) could revolutionize and democratize custom software development by extending it into jobs where computers have been a viable option before.
I think the opportunities for experienced Cocoa and Cocoa Touch programmers are huge, whatever Apple releases today.