Fischertechnik now has a robot kit that runs on Mac OS X. As usual with Fischertechnik: significantly more professional programming options, a significantly more professional-looking device, and a significantly higher overall price than Lego. Somehow a shame - I used to like Fischertechnik, but the stuff was simply too expensive to own in sufficient quantities. And again here - 255 euros just for the interface, it doesn't help that the construction kit itself only costs 170 euros. And autonomous robots are not possible with it, the whole thing is wired.
So I will probably continue to wait for Mindstorms NXT, because I already have a lot of material for Lego. And the RSXe are also fun.