Was the FileMerge application removed from OS X 10.7.3? I just updated to 10.7.3 and can no longer find the FileMerge application, which is part of the Xcode developer tools package. Did apple remove this in 10.7.3?

I've checked in my developer directory, and used Spotlight, but it is nowhere to be found.
With Xcode 4.3, Apple has moved the content of /Developer to the usual places for applications etc. Filemerge is accessible by starting Xcode and then accessing Xcode -> Open Developer Tool. If it's not listed there, select "More Developer Tools" to install it.

Physically it's part of Xcode.app (Xcode.app/Contents/Applications/FileMerge.app) and can be executed stand-alone by inspecting the package content of Xcode.app. If you really need it outside of Xcode often, you can also create an alias/symlink to start it directly (or just drag it into the Dock).