I had Borderlands GOTY (from Steam) running without too many issues with CXG 10.1 + OSX 10.6.8 (except, of course, the Dr. Zed and Moxxi DLCs). System specs are:
MBP 13", Mid-2010 - 2.4GHz C2D, 8GB RAM, 320M
I didn't have any registry hacks (outside of our favorite MouseWarpOverride), nor any real tweaks in the WillowEngine.ini (outside of clamping down on the DesiredMinFrameRate (28), and the Smoothing options so it'd be less jerky (28 - 32)).
However, with the update to 10.7 and CXG 10.1.1, Borderlands fails to render video. I was originally skipping the intro "movies" (2k/Gearbox/nVidia logo sequences), where I would only get a black screen, no audio. Changing resolutions did not help (tried 800x600, 1024x768, 1280x800). I enabled the intro movies to see if there was a different rendering problem, however, it looks like the issue may be related to audio. I could get the first few seconds of the 2k logo audio sequence, and then it would cut out. Video would never render. Command-Option-R or Command-Q were the only ways out.
The "-ONETHREAD" load option did help to get the logo sequences rendered, but it would still render a black screen with no audio there on out. At this point, only ending the process (in CXG's Task Manager).