Back in 1998 LEGO released their Mindstorms Robotic Invention System (RIS), and took the education and robot hobbyist communities (not to mention kids and kids-at-heart) by storm. The kitis RCX - a LEGO brick with a small battery-powered programmable computer, three sensor ports and three motor-control ports - opened up the world of amateur robotics that previously was only accessible to people willing to spend thousands of dollars on equipment and hundreds of hours on tedious assembly-language programming. Originally developed with the middle-school and younger high school audience (ages 12-16) in mind, the RIS featured a PC-based graphical programming environment that would gently introduce its audience to programming while not confusing them with many of the subtleties that more mature hackers face when using low-level assembly language programming or advanced programming languages like C, Java, or Lisp.
Once the hobbyists in the computer science community figured out the byte codes and infrared protocol used by LEGO, several homegrown programming environments and libraries sprouted up. The most notable has been Dave Baumis "Not Quite C" package, which was originally developed for the PC but has been ported to the Mac platform (OS X too!). The package allows one to use a subset of the C language to write high-level programs that are then compiled and transmitted to the RCX for autonomous execution.
Other than this environment and Pitscois Dacta programming environment, however, there is no way to program Mindstorms from a Mac. Unless, of course, one runs Virtual PC and then uses any of the PC-only environments. And, with the exception of RealTime 3.0, there is no way to remotely control an RCX from a desktop/laptop computer - something which, given the RCXis lack of floating point support and somewhat small memory (6K-10K, depending on what firmware one uses) would be desirable in supporting complex control programs. Plus, even RealTime 3.0 is not "scriptable," so one can only control an RCX by manually selecting functions from a menu.
You can find more information at the PowerBook Source Web site.