You can't :) The jabber architecture basically prevents this.
This seems similar to the issue with jabber:x:oob. You want to establish a connection to send some data, so you send someone an IP address and port number encapsulated in a URL. In the basic case you're sending your own address and the number of a port that your Jabber client just opened, but it's conceivable that some intermediate server could get involved as a reflector to get through firewalls/NAT.
So it seems you could initiate a NetMeeting / videoconference / whatever session by sending a particular message with an oob element that contains your IP address. You'd need some distinctive URL scheme � like "netmeeting:" or whatever instead of "http:" � to let the receiver know what sort of connection you want to open.
So in short it's not possible to find another Jabber client's IP address, but it's possible to reveal your own to that other client.
�Jens
