Reading about the 256MB RAM and the lack of swapping on the iPad/iPhone OS, I'm thinking that Apple ought to take a page from Nokia Maemo (soon Meego). On my ancient N800 (you note I keep mentioning that it is ancient), I can assign memory swap to one of the SD cards. That enables more apps to run concurrently before they enter a sleep mode (a little "zzz' on the application icon).
I see no reason why an iPad (or iPhone for that matter) could not have it's memory extended to the built in 16,32 or 64 GB of solid state RAM sitting in the iPad. Is it slower than the main 256MB? Probably. Is it as slow as a spinning disk? Absolutely not. Maybe we'll see something like that in the 4.0 OS (or 4.1) particularly for the iPad. But really Safari ought not have to reload tabbed pages. That just needs to stop.