For the record, this guy has been wearing actual computers.

Google glass is an accessory- essentially a bluetooth headset, display and camera built into glasses. The intelligence lives on the servers, and glass needs a bluetooth or wifi connection to talk to the net.

I think google's engaging in a bit of a PR swindle by making people think google glass is like an iPhone. It isn't, it needs and iPhone or android phone to connect to the net.

Consequently it can't replace a smartphone.

I'm also pretty dubious about the battery time it will get, even without having to run a local CPU.