The latest update is out now on Zune as well. Just updated mine and I now have a Full Charge Capacity of 1486mAh, when it previously was around 975mAh.
The device is discharging with Wifi and 3G data disabled at around 140mA.
The update didn't show up in Zune for me, so I used this trick which I read on another forum.
An easy trick to force an update to your phone. Using the Zune desktop (connect your phone), go to 'Settings' and 'Update'. Here Zune starts checking whether there is an update for your phone or not. After about 3 to 8 seconds, disconnect your network and wait untill your computer says 'Update found' (might take up to a minute or so). Then plug the network back in and start updating.This has all to do with the way the update process works. No update found does not necessarily mean there is no update, just that you're not allowed to get it yet. If the update has been scheduled for your device and you disconnect at the moment it finds an update (right before the Microsoft server sends the 'block this update'-signal), you will receive a Zune notification. Once you receive the update-message, you can continue the update process same as anyone else