Update 7/28/12

Version 2.0f6 works great on Mountain Lion.

Update

I installed the 2.1 app running the LegoMinsstroms???Edu.mpkg and then I followed the following instruction @ http://www.dansanderson.com/blog/2009/12/did-you-get-lego-mindstorms.html

This works for Lion as well.

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Here's the fix, thanks to nxtasy.org and the forum, with an important addendum from this thread:

Copy all of the files from the install CD to a folder on your desktop. You will be modifying an installer package to disable a piece of it.
Find the Parts folder, then open it and find either MindstormsUnivEdu.pkg or MindstormsUnivRet.pkg. (Mine is the latter, I assume that's the "retail" version vs. the "educational" version.) Right-click and select "Show Package Contents."
Open Contents, then Resources. Right-click the preflight file and select "Move to Trash."
Navigate back to the MindstormsUniv….pkg bundle and double-click it to start the installer. Follow the instructions to complete the installation.
Back in the Parts folder, double-click legodriver.pkg and follow the instructions.

You can now go to /Applications/LEGO MINDSTORMS NXT and double-click MINDSTORMS NXT.app to open the application. If you get an error about a file missing (error "1003"), make sure you did the last step with legodriver.pkg. You may still need to run the full installer (the one that offers to install Adobe Flash Player and requires that you reboot the computer) to install the engine directory.

Not functioning at all.

—-you can install it on loin by running LEGOMindstromsEngRet.mpkg. however when you run the application you get Error Code 1003:- "A required file is broken. " . I am still trying to figure out how to fix this.