Just chanced upon the new release of a Sony PSP based planetarium software, it even has GPS support with the PSP GPS adapter.
Planetarium Creator Ohira Takayuki Kanshuu: Home Star Portable
I'm hoping there will be an English port of it at some point. Its from SEGA and a Spin-off of the Homestar Planetarium "toys" they released last year. Looks really cool
Some links with info and screenshots.
http://www.1up.com/do/gameOverview?cId=3153895
http://kotaku.com/190756/