Regarding what i wish i could do with my iPad:
I could name things that you cant do, but it would take away from my point. Its not any one thing (ie photoshop, video encoding etc)
Not to sound cliche, but i wish it was an open platform. This device is so versatile, imagine all the things that could be done if it were. I am a believer that tablet computing will become a huge part of our culture. Science fiction stuff.
So with that, why cripple a device that could be so powerful? Why stifle innovation? Apple's locking of the file system means i can't upload assignments to my schools website. It's also a pain in the ass to transfer files without USB. For as much as Apple promotes seamless integration, the iPad sure doesn't seem to allow that. In order for a tablet to truly be the future, it must be allowed to breathe a little.
I probably see it differently than most. I think everyone will have tablets eventually.. and I think everyone will carry it with them. And maybe I'm a little biased, but I think that if someone has spent their life trying to master technology, they should be able to put that to good use.