I know you can, my friend Mitchell does. You probly have to put something like firefox on the memory card or something (its wifi so you just go to a hotspot and your set)
I dont know for certain, I'll have to ask him how he does it next time I see him. in the mean time.. *searches google*
Has some nice information. Apparently Mitchell wrote his own software to utilize it, Which doesn't suprise me. Pretty soon there will be alot of 3rd Party browsers out there for it, Should be interesting.
*Awaits Blah Messenger for the PSP to come out for download* XD