An often overlooked but important aspect of modern consoles is their ability to store data. It is very handy, from both a player and manufacturer's standpoint, to have your data on a flash card or internal storage drive. Handhelds have been overlooked for a long time in this aspect, but it seems that Sony might be considering a change of heart.
There are some rumors floating around that they are considering adding a HDD or other type of internal storage to the PSP. The idea stemmed from the increasing integration of the PlayStation 3 and the PSP, such as Sony announcing plans to let you purchase movies on the PS3 and then view them on the PSP. Also, following the relative failure of the UMD, Sony has incentive to try something new. I hope to hear more on this.