Since getting the set I've felt that the high color temp is too cool/blue and while the low temp setting is better it's a bit too yellowish. I've been meaning to do a grayscale calibration of the set using my i1 spectrophotometer, and finally got around to it tonight. The low color temp measured 5500 at the default settings which confirms the yellow cast I was seeing. So I went into the service menu and changed the green/red/blue gains using the i1 to dial in 6500K. The result looks much better IMHO. Although the settings below may not be exactly right for every set they may be closer than the factory defaults if you want to give them a try.
The procedure for getting into the service menu is listed elsewhere in this thread as well as the combined Mits DLP owner thread. The usual caveats apply, enter at your own risk and write down the original settings down if you want to be able to get back in case you screw something up. Here are the settings I arrived at:
6. GGL - 911
7. GRL - 990
8. GBL - 798
Note these only affect the "low" color temp, if you're using "high" you'd need to adjust GGH, GRH, and GBH.