I've been anxious to get a look at the IM client as well, but haven't had much luck. I've been thinking about posting, but have seem comments like "not ready yet", "still beta", etc., so I've been holding off, but figured now is as good as any time to jump in.
First off, I've been running 5.0, OSS only, since the first beta release, and I'm currently running RC2. Like Chewie71, I can't add anyone to my buddy list, and don't have the option to communicate with AOL, Yahoo!, etc. I can get to the point where I can add a new buddy, but when I click OK it doesn't get added to the Buddy List. Also in the Create New Buddy window my only option for IM Service is xmpp.
Phoenix, can you clarify this, or I guess provide more info. Currently with RC2 I have one test user logged in to Zimbra 5.0 RC2 on my PC and another logged in on my laptop. On either system I go to the IM tab and click New. It does bring up a new "conversation" window. However, when I type some text and hit enter nothing ever shows up on the recipient's end. I'm guessing I probably have something setup incorrectly, or not setup at all. However, as far as I can tell there is zero documentation on the IM client at this point, so I have no idea what I'm missing.The IM does work in RC2, I use it.