During the VSA dinner, some questions on ADS-B for gliders came up. The person who knows the most on this is Darryl Ramm, as he's been working this to both inform glider pilots and clarify equipment mix depending on your glider type. He gave a talk on this at the PASCO seminar a few months ago.

Some links to start with for background:

Darryl is working on some ADS-B pages, but until then he knows I'm posting this and may chime in.