Been working with Eclipse a lot recently www.eclipse.org. It's an IDE with strong component-nature, that allows others to add on well-integrated functionality to the system. It can be made to provide dev support, architecture/design support, etc.

I've been working on a plugin that allows teams to communicate and collaborate with one another directly within the Eclipse interface. Team members associated with a given Eclipse project are made aware of one another, can communicate via IM/chat/app sharing/file sharing, and do it in a context that is specifically designed for that particular group (i.e. with the functionality required for the team involved). See the following web page to get a copy for yourself and try it out. If you want to use it regularly, send me email at slewis@slewis.com.