I have been playing around with Google Talk It is quite nice, once again I like the look... But I do not see 'revolutionnary' features... Like Skype I was able to use it at work IM and Voice chat... I like the fact that they document how to work around their lack of platform support... I would like to have a mac version... I am surprised that Mac users in Google did not yet implement it! Fo developer perspective it is interesting to know that they use standard based protocol such as Jabber/XMPP, and they invite people to use the API (since open standard) and server... Take a look to the developer section of their documentation.