ananzjo: we're activly looking in to it, hope to have it working for you for the next release.
Quick few questions and a few steps that you can follow, if you wish...
Are you running Windows Vista? If so, is UAC enabled? And if so, does the problem go away when UAC is disabled? Also if UAC is enabled, you're not doing anything special to run explorer "as administrator" I assume? (doing so would definitely make it not work)
Also, MCP is no longer needed for tray functionality and might get in the way. After you've gone through the steps above to diagnose, I'd also recommend trying to get rid of SDMCP. In the next version I hope to include something that will take of this automatically. But anyways for diagnosis sake... End it's process, and go ahead and find the SDMCP exe and dll.... and rename them (put and "_old" after their filenames, so you can restore it later if you really need to). You can find SDMCP files in your "C:\Program Files\Common Files\Stardock" directory. Files you'll want to rename.... "mcpcore.dll" and "sdmcp.exe". (You can't just delete them as they will be "in use", but you should be able to rename them fine.) At this point, do a reboot, and they will no longer be in use. Try ObjectDock's SystemTray out then (preferably with UAC off if on Vista, but you can try it with it on too if you do in fact use UAC). Knowing if this fixes the problem for you or not would definitely help the situation for you and others as well

Sorry for the hassle, hopfully this will be up and running for you soon. Thank you!
Best Regards,
-Jeff Bargmann
ObjectDock Lead Developer