The PSP version of Savage Moon will be released via PSN on 22nd December for £6.29 or 7.99.
That's what producer Ana wrote on the European PlayStation blog and frankly I believe her.
Savage Moon's a tower defence game that takes place high in the sky in a place we call space. The PSP version, subtitled The Hera Campaign, has two new species and a brand new interface, plus unlockable vengeance mode and soundtracks.
There are shots and a video on the EU PS blog.