Techworld's Nancy Gohring reports today that Nokia has updated the operating system for its Wi-Fi Internet tablet, the Nokia 770, adding support for SIP-based voice over IP (VoIP) -- the device now comes pre-installed with Google Talk, and also supports instant messaging (IM) clients based on Jabber.

Ari Virtanen, Nokia's Vice President of Convergence Products, says the changes are in response to customer feedback: the number one customer request, he says, was for VoIP support.

"In a departure for Nokia, which is best known for developing products for the cellular industry, Nokia 770 doesn't come with built-in cellular support," Gohring writes. "Instead, it has Wi-Fi, although users can connect their cell phones via Bluetooth to use a cellular network to reach the Internet."

And Brighthand's Ed Hardy notes that Google Talk won't be the only VoIP option. "SIPphone Inc. intends to bring its Gizmo Project to this device," he writes. "This VoIP software will let users make and receive calls from public telephone networks."

Keep an eye on this one. There's got to be an ideal balance somewhere between the small form factor of a mobile phone and the functionality of a laptop -- and this looks like a very promising start.