Earlier quoted context omitted.
Or for half the price, the Unicomp EnduraPro. http://www.pckeyboard.com/page/FeaturedProducts/UB40PGA
A colleague of mine has that and the trackpoint on it is useless. I tried it and it feels super stiff, no acceleration, and the mouse buttons are very hard to press, too. The keyboard is very nice if you like buckling springs. Buy their normal keyboards if those are your thing, but don't buy the EnduraPro. It's nothing like a ThinkPad trackpoint.
The current version is the TrackPoint IV.
More on the topic, unfortunately does not include usage in external keyboards: http://www.thinkwiki.org/wiki/TrackPoint