Since they seem to be in the exploratory stages, it may be some time before we actually see the product on the market. It will also be interesting to see how the interoperability is achieved, since Google Talk uses Jabber/XMPP, which is pretty open, and Skype uses a completely proprietary protocol. My guess is Skype will incorporate the Jabber/XMPP to allow to talk to Google Talk, and to any other client that uses the same protocol. That way, they don’t have to open up their internal protocol to their competitor Google (Skype being owned by eBay, Google developing their own payment system to compete with PayPal, etc.).