Mountain Lion broke support for Absinthe, however there IS a work around until the devs get around to fixing it. Step 1. Download Absinthe. Step 2. Right click on Absinthe and select "Show package contents". Step 3. Navigate to /Contents/MacOS/ Step 4. Right click on "Absinthe 10.6" and select Open with > Terminal. Step 5. Terminal will launch the GUI and you can continue your jailbreak normally. Thought I'd share since I was faced with this problem this evening.