Angry Birds for Symbian gets two new birds and two new worlds
The update brings two new worlds, one golden egg world, and two new birds: Boomerang and the Steroid Bird. There's also a new splash screen, and the main dashboard theme changes based on the previous world.
The new version hasn't reached Nokia's Ovi Store yet, but you can update to it using the Update feature that shows up in the bottom right corner of the main dashboard inside your existing Angry Birds install. This will download a file to your device, which you should then run, as it will install the update.
Alternatively, you can grab the update file from SymbianWorld, and run it once you've downloaded it onto your smartphone.