IBM/Lenovo actually uses keyboards from a number of manufacturers: NMB, Chicony, and ALPS. Each have their own "feel." The general consensus is that the NMB keyboard is the best (I was lucky enough to get an NMB keyboard on my T60), but the Chicony seems to be winding up in most T-series laptops these days.

You can often find the NMB keyboard on eBay if you aren't fortunate enough to get one in your ThinkPad. Replacing the keyboard is a 5 minute job.