Service for the developer collaboration XMPP server share.java.net has been discontinued as of April 20, 2009.
Users who connect to share.java.net server from the NetBeans IDE via the Developer Collaboration plugin are being notified about this change during the login operation in the IDE, and after they download and install a plugin update from the NetBeans Update Center.
After April 20 share.java.net users have to migrate to alternate servers.
One available migration option is the OpenFire XMPP server. The Developer Collaboration plugin functionality in the NetBeans IDE 6.5 and 6.1 has been tested against the latest version of OpenFire XMPP server, version 3.6.3. Instructions for setting up a private OpenFire XMPP server to work with Developer Collaboration support in the NetBeans IDE can be found on the CollabServer wiki page.
Project Kenai is well integrated into the NetBeans IDE 6.7 and includes a chat server among its services that covers the developer collaboration functionality.