Free Internal Office Instant Message (IM) Server

q: Today the customer was looking for a free internal application to allow their employees to chat over IM with each other but not their friends or services.

a: The Answer is OpenFire -  http://www.igniterealtime.org/projects/openfire/index.jsp  We've been very impressed with the features of the product so far.  We installed Openfire on a rarely used workstation.  Then installed Spark (the IM Client) on everyone's workstations across two offices and now they can all chat.

• UPDATE: We discovered SparkWeb - this is a small collection of files that can be thrown in an IIS Virtual Directory to grant users access to the Chat Server without having to install the client.
• UPDATE: Today we discovered OpenFire simply uses the Jabber protocol and if 5223 is allowed through the FW you can use IM Clients like Digsby to connect to the OpenFire Server from outside of the firewall.