Codeweavers makes Crossover Games, a commercial version of Wine that allows you to play various Windows games on Mac and Linux:
Based on the latest Wine Games development work, CrossOver Games allows Mac and Linux users to run their favorite Windows games in the environment of their choice. No rebooting, no switching to a virtual machine, and no Windows Operating System license required; CrossOver gives you the best performance possible if you’re not running on Windows.
Now they have a page where their registered users can vote for them to arrange Fallout 3 support on the application. Thanks Patrick.