I got an iPad 3G the day they came out and have been using it a lot in the subsequent few weeks. I think it could be the ideal computer for the cyclist (though not a cycling computer!). I have a MacBook Pro which I occasionally have taken with me to meetings and work and stuff and I worry about it because it's got a 500 Gig hard drive in it which is getting bumped and jostled. Sure, you can buy big solid state hard drives, but they cost a fortune. Sure, the odd ride here and there isn't going to hurt it, but a day-in, day-out commute can't be healthy for the hard drive. Also, it weights like 5 pounds.
You could do a MacBook Air (with SSD if you're worried about the hard drive) but those are even more expensive and still weigh three pounds.
Or you can do an iPad. It weighs 1.6 pounds and the separate BlueTooth keyboard I have must take it over 2, although you can at least leave the keyboard behind if you don't need it on a given day. The battery life is nice and long, the screen is lovely and big, the Maps feature is superb when mated with the 3G's GPS, and there's no moving parts. Worried about dampness? Get an Orltieb document case for it, basically a heavy-duty roll top ZipLoc baggie. I know, I know, it's not a real computer, you can't run the heavy-duty spreadsheets on it that I routinely work with, the Pages word processor has it's limitations and it's not possible to print at the moment (there are third-party software packages for this, but I haven't tried them), but for note taking and email and web reading and writing this blog entry, the device works great.
I still use the MacBook for the serious work in life, long documents and big Excel spreadsheets (run in Windows on the Mac) at home, photo editing and all that sort of thing, but the iPad makes a smaller, lighter and surprisingly useful device for the cycling geek.