In Gamespot's DICE coverage of Phil Harrison's Q&A, they had a few mentions of PSP. Firstly that there will be deeper online functionality later this year. Specifics weren't given, but I personally would like the ability to have most web pages finally work on the PSP. Though it could also be a hint at downloadable PS1 games finally being capable without a PS3.
The homebrew community may have another reason to disagree wtih Phil Harrison after the event.Also during a talk about homebrew, someone asked about the PSP's role in it. Phil claimed that the system wasn't well-suited for homebrew. Newsweek's N'Gai Croal then mentioned Dark_Alex's work and Phil had some sort of cryptic response about future announcements.
So all and all, not a whole lot of new PSP info so far, but hopefully GDC will bring us more news.
[Update 1: "This year we'll be adding some functionality to the PSP that will unify our approach," Harrison reveals in an interview with Gamasutra. Seems like PSP might pick up some of the cooler network options of the PS3.]