I would put some truth into this - for a few reasons. The biggest one being that Sony and Logitech have worked together in the past on input devices - take a guess who designed the entire input subsystem on the PS3? Yep, Logitech!
Furthermore, it keeps Sony's hands somewhat "clean", as in providing support, plus from fanboys yelling that it should have been included, etc.
Then again, I really don't know why the PSP is still around - either upgrade it with a newer model, or kill it off, this limbo that it is in is about as sad as the new gigantic NDS!