The bitcoin wallet is stored at ~/Library/Application Support/Bitcoin/. All versions look to the same user directory location for your wallet.
Yet I did a search and couldn't find bitcoin anywhere on my comp. Also why did it disappear from my desktop?
You don't need to search for your wallet, just know it is saved in a different place than the Bitcoin client software. I was explaining why you still have your bitcoins and addresses even after reinstalling the Bitcoin software - even if you delete the program, it leaves behind your Bitcoin data, because it could have money in it.