In July, we posted an updated version of In Harmony with Eclipse (I say we, but Alexey did the work). This new version features the Eclipse SDK 3.3 on top of Harmony 5.0M2. There are downloads for Windows and Linux.
The Harmony developers are working hard to make their runtime environment fully functional; and they’re doing a great job of it. I’ve been able to run Eclipse and Tomcat using it for months. The best part is that the Harmony developers are actively trying to identify and fix problem spots. A recent note on the cdt-dev mailing list is just one example of the Harmony developers reaching into our community to help solve problems.
The moral of the story is that if you’re having a problem with Harmony, report it.
Eclipse Hints, Tips, and Random Musings 
It did take a while for the Harmony gang, or at least Alexey to pick up that the bug was blocking using CDT with Harmony. But I’m glad he’s leading the charge. I’d love to have Harmony as the JVM for Wascana, http://wascana.sourceforge.net, an open source distribution to showcase CDT for desktop development. Relying on Sun’s “freely redistributable” JRE is unsettling while Harmony offers a much more friendly licensing.
There isn’t a version of Harmony for the Mac yet. Porting it isn’t likely to be easy, especially for the PPC variant, although an Intel one might be around the corner.
However, every Mac has Java installed as part of the OS, so there’s also less of a driver for it to happen, although I don’t doubt that some day it might happen.
Alex, you’re right and oops (not sure where my head was). I’ll update the post.