Spotlight Cmd+Enter to open containing folder does not work
There is a bug in 10.8.2 that intermittently makes revealing files in Finder stop working. When that happens, Archive Utility also stops responding whenever you try to extract archives.

As a workaround, you can terminate the appleeventsd process from Activity Monitor or with sudo killall -kill appleeventsd (without -kill the process is sent a TERM signal and other processes stop responding). The issue will probably return in a few days or hours though.