Earlier this week, Truphone announced interoperability with GoogleTalk. Now Truphone users can call GoogleTalk users, and vice versa. On-net Truphone users appear as online GoogleTalk users, and now any GoogleTalk user and Truphone user can talk for free, all via the magic of XMPP.
Want to know how to do it? The Truphone lads have even made a cheap and cheerful home video. Enjoy!