Chronic Dev team has just released the Mac version of its iDevice jailbreaking tool, Greenpois0n.Just like its windows counter part, its pretty much a one button deal. Just follow along with its prompts to help you get into DFU mode. Just about as simple as it gets. Go get it here If you really need a tutorial, check this out from the windows version here.
Greenpois0n for Mac now released. Get it from http://greenpois0n.com