I had the same problem today with a fresh Debian testing (3.0.0 kernel) installation on a 900X1B: high cpu temperature and a lot of fan noise (and short battery life).
Following the instructions found herehttp://www.phoronix.com/scan.php?page=article&item=intel_i915_power&num=1
the temperature has dropped by 15 °C and the fan noise has disappeared, I haven't tested the battery but comments here http://www.omgubuntu.co.uk/2011/11/linux-power-regression-overheating-problem-on-thinkpad-fixed/
claim battery life more than doubles using this configuration.
I used this for a few hours without any problem, compositing works fine (in KDE).