A better filesystem and a better user interface. Haiku filesystem goes in the right direction (read the interview to Kevin Musick, BeServed author). I happily read als that the Sugar UI will be developed also for other hardware that is not OLPC, which is good. I had the chance to play with a XO laptop and I loved it, even though the machine is slow (it was an early prototype from the AMD Italy folks).
Then there is ITSME, for which I hope to see soon something. There is lots to be done.