Ngmoco takes classic gaming concepts and genres, re-interprets them for the iPhone, and then makes them look better than anyone can believe an iPhone game can look. Star Defense, a galaxy-spanning take on tower defense, is no exception.

Shown off yesterday during the WWDC 2009 keynote, not only does Star Defense let you travel from planet to planet, touch, spin, and zoom your way around, deploy your firepower, and try to keep ahead of the deadly hoards of S'rath out to harshen your tower's mellow, but it lets you challenge your friends over Facebook or Twitter for extra fun.

Star Defense is available now [$5.99 - iTunes link]

When iPhone 3.0 launches on June 17, Star Defense will use in-app purchases for expansion packs. For $2.99, for example, you can buy another galaxy of planets. A Plus Network will also allow for network play, leader-boards, and other online gaming features.

I had a chance to try the pre-release version out during the media tournament, and even though I didn't fare to well in the rankings, I had skads of fun.

Think you can out score me? (Yeah, I do too...)