Mark Overmars has posted a Release Candidate of Game Maker 8 online for users to test.
It can be downloaded here (5.47 MB). As with the previous beta version bugs should be posted on the mantis bug tracker.
“This is the RELEASE CANDIDATE of Game Maker 8.0 that is only meant for testing. It will stop working at the end of October 2009. The same applies to all games created with this beta version.”