According to the official PlayStation UK site, the recent PSP firmware 3.72 update includes a new Remote Play feature called Remote Start, which allows users to remotely turn on their PS3 from the PSP. Coincidentally, this was one of the rumored features for the upcoming PS3 firmware 2.00 update.
Moreover, to use the feature, firmware 2.00 must be installed on your PS3. Now, the only question is, when is the 2.00 update coming?