After upgrading to Ubuntu Intrepid Ibex with a Dell Latitude D630 (nVidia Quadro NVS 135M GPU) and using the nVidia driver 177, my GPU fan started to run for two seconds, pause for one, repeat that a few times, and finally run on full speed endlessly. Others had similar problems, e.g. with a Dell XPS M1330 with GeForce 8400M GS, as can be read in this
bug report.
One workaround is to switch back to the nVidia 173 driver (which however is not marked as recommended). Another option is to upgrade to the newest Dell BIOS (in my case A13, but A12 also appears to work).