As this expansion takes place, Google is allowing current Explorers to send up to three invitations to friends. Of course, there's still that $1,500 price that will serve as a sticking point. At the same time, all Explorers will be able to swap out their existing Glass hardware for a new version. This is a one-time only swap.
More details on the swap-out program are available here. Explorers need take any steps of their own. Google wil proactively notify them in November with next steps for the swap program.
Nicely, though who have regretted their prior color choice can use this one-time opportunity to switch colors.
Not only will the hardware be upgraded for new internal components and little "tweaks" to make Glass better, it has been redesigned to allow Glass to work with "future lines of shades" as well as the previously promised ability to use Glass with prescription eyeglasss. Also included will be a mono earbud, replacing the prior bone conduction speaker in the current version.