It's essentially a large multi-touch iPhone. It runs with the iPhone SDK, so it will run all the iPhone apps natively, plus, (and I'm reading between what Steve Jobs said and didn't say:) unfortunately, whatever Apple decides to sell you through the app store. You also can't make phone calls from it, so it's more of an iTouch than an iPhone.
International versions (WiFi only) 60 days from now.
Screen: 9.7" diagonal multi-touch. As big as two paperback pages side by side when in landscape mode.
WiFi only models: (available 60 days from now)
16 GB: USD 499
32 GB; $599
64 GB: $699
3G + WiFi models: (via AT&T: $15/mo for 250MB/mo data, or $30/mo "unlimited" data, which of course doesn't mean unlimited).
(available 90 days from now in US, no news about international availability)
16 GB: $629
32 GB: $729
64 GB: $829
Note that these prices are for AT&T only. Looks like there will be lots more frustration ahead for AT&T iPad users, with users blaming AT&T's network, and AT&T blaming Apple. However, the 3G SIM chip is unlocked, meaning you can use it with any carrier supporting a GSM network. That unfortunately rules out Verizon, which uses CDMA.
Battery life: supposedly 10 hours playing video continuously.
eBook reader: iBooks. Has deals with various publishers (iBookstore). Supports ePub format. No news on PDF, but I would assume it's supported, I can't imagine why it wouldn't be. No news on whether Blio (Ray Kurzweil's reader) will be available on the iPad. My guess is not, since the Apple app store tends to reject applications that duplicate Apple's own functionality.
I'd get this thing in an instant if they supported 3rd party apps. But if it seems that this is just a bigger iTouch with an ebook reader app... no thanks.