I searched through the FAQ, wiki, and forum and the only reference I was able to find for locating this file was that it should be in ~/Library/Application Support/Bitcoin/... but I don't have a Bitcoin folder in my Application Support folder and am unable to find wallet.dat anywhere on my computer.
Hmm... that's where mine is located. Did you search using the Finder or through a terminal? If through the finder, try opening a terminal and typing the command:
find / -name 'wallet.dat'