ITT VIS announced an update for IDL on OS X today:

A new update for IDL on Macintosh computers is now available. The IDL 7.0.4 release adds support for Macintosh Intel 64-bit architecture on OS X 10.5. IDL 7.0.4 also fixes two issues that impacted all supported Macintosh platforms: CR49844 – “Creation of Semaphores Fails under Mac OS X 10.5”, and CR51198/CR51412 – “CURSOR/RDPIX Procedures not Working Correctly on OS X”.

Download, full release notes.