Android Market. I've been one of the beta testers.
Here's my five-star Market review:
This is easily and by far the best astronomy software for Android devices. I think it's better than Stellarium for the desktop. Superb coverage of the solar system (planets, minor planets and comets) and deep sky objects. Good information on various objects. It's great to have outlines of wide deep sky objects. The Pro version adds tons of stars. From my experience with Palm apps, for serious star-hopping and identifying of faint objects with a decently sized telescope (I have a 13"), one really should benefit from having the greater depth of coverage that the Pro version provides over the Plus version. Hint 1: If you have a somewhat slower device, you can greatly improve smoothness by setting the Horizon to Transparent with Line and turning off Milky Way textures. Hint 2; While the built-in night mode works well, it doesn't affect the on-screen keyboard keyboard or any soft keys on screen if your device have them. For rooted devices, you can install ChainFire3D and use its night mode, and for unrooted devices, you might try my own free "GB keyboard with optional night mode".