I got the chance to try out the 5d mark iii today, so I installed Lightroom 4 on my computer. After realizing the files wouldn't load correctly, I researched the issue a bit and found out about the 4.1 RC2 download. I downloaded it and ran through the installer on my computer (iMac, OSX Lion 10.7.2) and everything seemed fine, yet when I open Lightroom it still reads as version 4.0, and won't import the RAW files from the mark iii. I tried restarting, re-downloading, etc, and have had no luck. Any help would be much appreciated!
All, I spent about 2 hours with Adobe Technical Support yesterday and got it to work.
Let me know if this worked for you!