yesu
So if you go to this directory, there is no such file named minecraft.jar in it?
~/Library/Application\ Support/minecraft/bin/
If it's not showing,...
Open terminal, type these two commands.
"cd ~/Library/Application\ Support/minecraft/bin/minecraft.jar "
"ls"
If Minecraft.jar is not showing, then do a search for it, if you have run minecraft then it should be present on your hard drive.