Google has made small tweaks to Glass throughout the Explorer program, but today the company has announced a real spec bump. All Glass units shipping from now on will have 2GB of RAM instead of 1GB. There will also be a new viewfinder mode when taking pictures and some more cards. It's not all sunshine and lollipops, though. Current Glass Explorers should take a deep breath – Google won't be swapping out the old version for the new one.
The additional RAM will allow more Glassware apps to run in the background, which is good now that the catalog is starting to fill out a bit. Glassware apps should start up a bit faster as well. Glass can be sluggish in its current form, so this is a welcome improvement. It does sound like the device will still ship with the ancient TI OMAP processor, though. The new Glass units will have slightly larger batteries than launch units did, but that actually started with all units a few months ago (it's not unique to the new rev).
On the software side, Glass will now have a viewfinder frame to help you take better snapshots, as well as Google Now cards for remembering your parking spot and tracking packages. The cards actually rolled out on Android a few months ago. Presumably these features will come to original units too, but Google hasn't explained how updates are going to work on the less capable version. Maybe it's the end of the line?
Glass Explorers will probably be bummed about being stuck with the old hardware. This is especially true after Google already swapped out units last year for the version tweaked for use with prescription lenses. It was $1500, but Glass was always presented as a developer device. You can't be too upset, but I'm sure there will be Change.org petitions anyway.