During his brief TGS keynote today Kaz Hirai demonstrated the ability to turn your PLAYSTATION 3 on over the Internet using the Playstation Portable. The new feature will be hitting the portable in a future firmware update.
The update will also add the ability to put your PS3 to sleep remotely.
Other Remote Play Applications shown during the keynote included the ability to use the PSP as a second screen for Formula 1 Racing and using multiple PSPs as PS3 controllers. In the future it looks like that PS3s will be able to connect to each other to view multimedia on remote consoles, with multiple PSPs acting as PLAYSTATION 3 controllers.