This second pair can be purchased and given out to a friend or family member. So far, Google has sold Google Glass at Google I/O and has given away 8000 pair in a contest. Google also allowed each Explorer to invite three others to join the program at $1500 a pop. Now, an additional pair can be purchased for the member's own use or for a friend.
Google is smartly broadening out ownership of Google Glass in preparation for the day when the device can be bought on a whim.
source: GlassAlmanac via RedmondPie