Teachers at our school were beginning to ask about the possibility of adding Instant Messaging functionality to our Learning Platform, so I turned to Office Communications Server 2007. Today I got it all installed and working.
The installation wasn't as smooth as I'd hoped, this was due to some remnants of an old Live Communication Server 2005 installation we had messed around with a few years ago. Our Active Directory was a little confused to say the least and when trying to activate the new OCS 2007 server I was confronted with an error; 0xC3EC7814 Pool is not ready. When I first installed OCS2007 it seemed to be tying itself to the wrong location in AD, opening up ADSIEdit confirmed this.
In ADSIEdit, when I expanded the Domain > System > Policies > GUID of the Default Domain Policy, the RTC information was residing there. The correct location is Domain > System > Microsoft > RTC Service > Pools. I'm guessing if yours doesn't look like the screenshot below, you'll get the same error:

The solution for me was to run the following commands to unprep both our domains, then unprep our forest.
LCSCmd.exe /Domain[:
] /Action:DomainUnPrep
LCSCmd.exe /Forest[:] /Action:ForestUnprep
Then from the OCS setup, prep the domain and forest again from scratch, installation was then successful.
Now it's all working, i'm very impressed. From within Sharepoint or Outlook (anywhere you see a person's name basically!) you can see their online presence (green dot for online, red dot for offline etc) and if you want, start an instant messaging session with them or transfer files etc.
