“Finder” icon missing in Dock after 10.6.6 update

Turns out that if you change the icons manually you might cause this issue to yourself.  jazzdude00021 explains below:

I did some exploring into Dock.app/Contents/Resources and found the remains of a self-done Finder icon mod that I did awhile back. Apparently Dock and Exposé use their own Finder.icns file located at /System/Library/CoreServices/Dock.app/Contents/Resources. I had altered this file along with Finder.apps .icns file to mod the icon manually, however I must not have changed it back properly. My guess is that during the update from Finder v 10.6.6 to v.10.6.7 the installer didnt handle it right because of my modifications. Thanks for the help to everyone who offered.

via Apple – Support – Discussions -.