[csallen]

I'd assume the video recording is more battery-intensive than the processing. Also, if you offload the processing to the smartphone, then it'll be necessary for Glass to be connected to your phone, which means wifi and/or bluetooth, which only drains the battery more.

[dm2]

It might be a challenge but there's no need to completely dismiss the possibility.

Here is a $5 keychain that can record for 1.5 hours. http://www.amazon.com/808-Car-Chain-Camera-Recorder/dp/B0084...

I'm sure Google and the countless engineers and scientists working on advanced battery technology could make something work for a reasonably long amount of time.

And there's no reason that you couldn't put a laptop size battery in a bookbag with a cord to the glasses and have an all day charge. Either 3 hrs without the optional extra battery or 24 hrs with the 3 lbs bookbag battery, that doesn't sound so bad to me, at least until we create better batteries.

[TeMPOraL]

The new Bluetooth Low Energy could help a bit with that a bit.

[keeperofdakeys]

From my reading, Bluetooth LE isn't so "low energy" when you send lots of data, http://en.wikipedia.org/wiki/Bluetooth_low_energy#Radio_inte.... In the end, you still need to use a bit of power.