Yes, that one feature I've been the most excited about for my PSP requires a PS3...or, as you may see it, Sony requires a PS3 to play PS1 games.
But I have faith. Maybe Sony will support WiFi transfers one day, over the PS4. And here is a video of their sweet emulator in action for those who are also itching to play some Twisted Metal 2 again. Notice that you can button map as a standard option. That's really nice for old games on new systems, unlike how Nintendo's classic line for the GBA has new button configurations for Super Mario World that ensure you not only will suck, but have absolutely no fun playing your all time favorite game.