It's pretty much agreed that the magical thing about the Apple tablet, the reason it could succeed where every other has failed, is going to be the interface. The software. But what's under the hood?
There are two arbiters of what's inside the tablet. The software, and the battery. If it's running an enhanced version of the iPhone OS, which seems likely, that says a lot. If you not-so-unreasonably expect 4-6 hours of usage out of this thing, it also says a lot. (Apple product rule: There's never enough battery life.) Together, they scream mobile guts.
The last three iPhones have run on processors using the ARM architecture, like basically every other smartphone on the planet. The iPhone OS is designed to run on ARM processors, so if the tablet's using iPhone OS, logic and Occam's Razor says, it's running on ARM too. But, you're asking, how's a chip architecture that's used in smartphones gonna power a big ol' tablet?
I talked to Ars Technica's chip maven Jon Stokes about tablet silicon for a while. Even going down the ARM path, there's a couple of ways to go about it. A persistent (and plausible) rumor is that the little chip company Apple bought, PA Semi, is finally debuting their wares in the Apple tablet. Previously, PA Semi worked on the Power architecture (remember PowerPC?), but what they excelled at, Stokes says, was creating incredibly efficient chips. So it's possible they were put to work on a chip for the tablet using the ARM architecture, especially given ARM's comments implying Apple's an ARM licensee.
Another ARM possibility is a custom system on a chip using the ARM Cortex A9, which is designed for smartbooks (those weirdly nebulous things between a netbook and a laptop). It's the heart of Nvidia's Tegra2 wonderchip, for instance, which is itself in tablets, like the very neat Adam one we saw at CES. The Cortex A9 is multi-core, fast and power efficient, even if it's outgunned on straight performance by Intel's Atom. (For more on the Intel/ARM device chasm, check out this piece by Stokes.) The major "problem" with this possibility is that the Cortex A9 is vapor at the moment (much like the tablet, oho), and hasn't shown up in anything actually shipping yet.
The other major piece of silicon to worry about is graphics. How pumped are the tablet's graphics powers going to be? Gaming could be a huge deal, and we've heard EA is all over the tablet. But are the games just going to be, uh, supersized versions of iPhone games? Again, if it's a big(ger) iPhone, Apple could license a PowerVR graphics part, like they've used in the iPhone 3GS, or perhaps even one from Qualcomm, who picked up AMD's Imageon mobile graphics a year ago. Don't expect anything crazy, like a fire-breathing GeForce 285 GTX. Like Stokes says, sticking with ARM makes sense if they're expanding on that platform. What we could see, maybe, is a dedicated HD video decoder that's popping up in some netbooks to handle H.264 video.
The only other real consideration, I think, is the screen. AMOLED isn't happening. Not only would it be too expensive, no one's actually mass producing 10-inch AMOLED panels—not enough for millions of tablets, anyway. Pixel Qi's screen tech, as much as I love it, is too rough around the edges, even if it very conveniently comes in a 10-inch size. So! Conventional LED-backlit LCD it probably is. The resolution is probably, at minimum, 1280x720 but probably more. Why? Pixel density. A 10-inch, 1280x720 screen is roughly 138ppi, lower than the iPhone's 163ppi or the new iMac's 208ppi. If you're going to seriously read on this thing, the higher the pixel density, the better.
And, uh, networking. Wi-Fi, how could it not? Supposedly, it'll have 3G. From which carrier(s), who knows? If it's on Verizon, it'll probably be on AT&T, too. Everything else, like RAM and storage, I'd argue, is nearly inconsequential, at least in terms of how you'll use it. Some gigabytes of flash-based storage that's a multiple of 16, like 64GB or 128GB. If it multitasks, it'll need more RAM, not less. It'll have a headphone jack. Maybe a camera (more likely yes than no, is the latest 'consenus'). People would like it to take an SD card, like the current MacBook Pros, but it probably won't. Oh, here's a real quandary: Real USB port, or iPod dock connector? We'd guess the latter. Hmmm!
The bottom line is that, for whatever specifics we might be wrong about thanks to secret hardware partnerships, it's probably going to look a lot more like a (big) smartphone inside than hulking notebook. Just like the outside.