"January, 2009--The new version of Star Walk contains links to wiki articles for practically all celestial bodies. For example, after choosing an object and reading info about it you may tap "W" to go directly to the Wikipedia article devoted to this star, planet, Messier object, constellation or meteor shower. After reading, you may return to Star Walk to continue observing the night sky."
This is really a cool application that I highly recommend for the amatuer astronomer and student (see my review here). The new version offers some good features that I haven't yet tried, but am looking forward to doing so very soon. Go here to learn more, or simply search out Star Walk in the App store.