You can stay in contact with everyone in your friends list (Chat), turn on your camera (to see if the dog is chew'n the couch, carpet, or another controller), spool movies off the PS3 harddrive too... Very cool, extends the PSN (and store) to your PSP while you on the move in a WiFi hotspot, like work, school, malls, Starbucks, and even now... McDonalds
When I'm out of the house, the PS3 is set to remote and my PSP is in my hand...
Take care,