The iphone 3.2 sdk does not support the iphones and ipod touches.
But there are new apis in the sdk, all of which are just for the ipad. There is an api to handle documents much like a desktop os. Some new kind of views etc. etc.
But this ipad is very iphnoeish down to the OS level. So i believe ra1ndrop would also work on it ????? it can be jailbroken and then we have multitasking on it. wohoo ? not really! official multitasking support would mean $$ opportunities.
They say its another gold rush, i am not sure. I would hope for one but do people have more 500$ to burn after they have already burned/are burning quite a huge sum on the iphone?
But any ways, any other mobile os (except windows mobile and blackberry) would be good on it. Symbian, Maemo, Android or WebOS.