It also sorted issues with the camera and is well worth installing if you're still on 1.5
It will wipe everything on your phone so make sure you back up first.
Also consider going to a custom 2.1 as you'll find it much faster, smoother & less of a battery hog. The FLB one on Modaco is excellent and can be found here -
FLB-Mod (2.1 based rom with tweaks) - Android @ MoDaCo