Hi I have the same problem.
Made a bootable USB stick with Fedora-17-x86_64-Live-Desktop.iso following the instructions at http://anee.me/installing-fedora-on-mac-book-pro/
I have a 24-inch, Early 2009 iMac with:
Processor 3.06 GHz Intel Core 2 Duo
Graphics NVIDIA GeForce GT 130 512 MB
Software Mac OS X Lion 10.7.5 (11G63)
When I boot with USB stick in and holding the Option Key I see the Fedora boot icon.
When I click it I get the initial Fedora screen with the 8 sec countdown for menu selection
Then no matter which of the two menu options I select, the next screen I see is a black screen with some random color patterns. I have tried different screen resolution settings but i get the same patters (just different size)
I was able to successfully install F17 on a different iMac running OS X Snow Leopard.
Has anyone on this forum been able to successfully install and run F17 on Mountain Lion?
Any pointers are greatly appreciated.