Gingerbread -- Android 2.3 -- despite being a "dot" release (aka minor), actually brought some fairly major changes to the Android platform. (It also brought us the statue you see above).
Cosmetically, nothing changed that much. The notification bar at the top of the screen went black, and the signal strength and battery indicators turned green. Many had been hoping Gingerbread would contain the handiwork of Matias Duarte, who led Palm's webOS UI and now is user experience director for Android. But it looks like we'll have to wait for Ice Cream Sandwich for that one.
Another big question you'll ask is "Will my phone be upgraded to Gingerbread?" For the first half of 2011, far too many phones launched without it. But slowly, our unofficial list of phones is starting to see upgrades.