Pleas add support for Microsoft Communicator networks commonly found in corporate networks. Also known as "LCS" it is very similar to SIP/SIMPLE.

More details available at:

http://forum.digsby.com/viewtopic.php?id=146

Adding this will remove a major limitation for adoption in corporate environments, also it should be a major stepping stone to providing SIP/SIMPLE which is a standard used in other IM systems based around VoIP and Unified Communications.