Yet about Google Call

Due the amount of comments and emails received, I will reply to them in a post.

• How does the Authentication works?
• That is one key reason for using their established XMPP channel for placing the calls. The user is already authenticated in GMail and Google Talk. So the request is sent through the authenticated XMPP network to their XMPP Component responsible to offer SIP Gateway. From that moment one the component will convert the Jingle Signaling from the Google Talk to SIP and use your Google credentials to authenticate in their SIP Services.
• Which Codec is being used?
• G711 is the only one that I could trace, although the Plug-In indeed support iLBC and others. The reason behind it, is that G711 is a supported codec in most all PSTN, Media Gateway or other interconnection with Legacy Telecom. Alternatives would be transcode, which is out of the question due CPU load, drop of quality etc... Or use proprietary G729 which requires the payment of extremely high royalties per client/channel.
• Will they succeed in making money?
• Google "Cows" may produce some "milk", but I doubt Google consider that as an important income resource. The feature is much more related with PR and positioning about THE REALTIME company, than anything else. Having most of what Skype does in their closed client, in a browser and using open technologies is a direct confront to Skype's model. IMHO, Phone Numbers are dead, and will be ripped out of the market in less than 5 years from now. 
• Are the API for Audio/Video Streaming available for third-party usage?
• That I could not figure out. Tried document or formal info from Google without success. May someone could assist us on that matter with some Javascript reverse engineering, or a Google guy, that wanna share that with us. Please let us know :)
•  Is there any client supporting it already?
• No, it is not yet available in any client that I'm aware. But I bet that as soon Google appears with a formal specification and documentation, that will happen very very fast.

Thanks for all the questions, I hope I have answered most of it.