Carina Software demoed their Sky Voyager application which is a virtual planetarium that has a large database of stars and deep sky objects. It also supports the iPhone 3GS compass to identify stars and objects by holding your iPhone up to the sky.
The app also supports their SkyFi wireless adapter which provides a serial interface for remote telescope control directly from your iPhone.
Macworld hosted a DEMO presentation showing off 6 of the "best of" products being shown at the expo.