The beta plugin has been tested and is functioning fine. I haven’t tried the stable version, but it should (in theory) work with no problems at all. If you try it and have any troubles then let me know and I’ll fix whatever bug there may be. I am 99.99999999% certain that it will work though.
I’ve now installed WordPress 2.5RC1 on the demo site and it is functioning perfectly. So to answer your question, yes, the current plugin (and the new beta) is compatible with WordPress 2.5RC1.