Is there a way to invite gtalk users to a room?

Hi,

we have installed openfire and we are looking for a way to invite external users to chat rooms (for example users from gtalk), so they can be part of openfire chat rooms.

Is it possible to do this and if yes how?

I will appreciate every info in this matter.

Thanks in advanced!

Probably server to server configuration will do the job, but i want to hear your opinions and comments for this. Also yor comments for server 2 server if it will do what we need.