Since the hdaps module doesn't support many newer Thinkpad models (mine included) and because the tp_smapi module is said to be better, I used the latter one in Hardy (named hdaps_ec) to support the integrated acceleration sensors.
But since I upgraded to Intrepid the hdaps_ec module is missing. (in both 2.6.27-6-generic and 2.6.27-7-generic)
A "locate hdaps_ec" only yields the module of the 2.6.24-21-generic kernel...
There are many people experiencing this problem, but the comment this in bug reports saying that hdaps doesn't support their model.
See e.g. #274512