The collective efforts of.. like uh two people xD to archive all things related to PSM
That said, there arent really that many people interested in PSM so it cant be helped..
Have a look around though, i got stuff for end-users and developers alike!
Under "Library" section you can find info on every PSM Game ever made. and
Under "Development Tools" section you can find SDK's and Unity Builds, as well as Homebrew PSDP Packages
Dont have a PSVita? or want to play PSM games on your computer? Download PSMUI 1.0