The update to version XE9 started hitting Google Glass a week ago, and now the full factory image has been posted on Google's developer site for interested parties to tinker with. This is a bit longer than past updates have taken to arrive in full system image form. The download clocks in at 327MB, which is about what all the updates have been.
The system images aren't really for average users who are just exploring with Glass. This is for advanced users who are hacking and modding Glass and need to flash the system fresh from time to time. Google has also posted (as it tends to do) the rooted bootloader for XE9 to make it easy to gain root. That, of course, comes with the caveat that rooting voids the warranty.
Grab the updates below, but use caution. That $1500 face computer isn't exactly easy to replace.