A new Nokia mobile phone, the E60, has an embedded SIP client in it. That's great news for companies like BridgePort Networks, as they are out promoting the idea of mobile network traffic being easily routed over an IP network that can terminate on a SIP endpoint.
Phones like the E60 will likely be hot items in places like New York City. Anyone who has ever walked into a building and lost cell service will love to be on a client's personal hot spot.
As such I'm seeing the need for dual networks inside most offices. One for the employees and another for the visitors. That way security is maintained, but convenience to guests becomes the order of the day.