After several months of non-intensive work I managed to make a public release of the IDEtalk plugin for IntelliJ IDEA.
You can exchange stacktraces, view open files of a user from your contact list, and open local version of the user's file. Currently it supports IntelliJ IDEA 4.5.x/5.0 EAP and uses P2P connections in the local network (no specific server installation is required).
I'm going to add chat and Jabber support in the next release.
More information and installation instructions can be found at http://www.idetalk.com
Looking forward for your comments and feature requests!