OK, I think there were two sessions for these; one at 10:30 am and the other right after it at 11:30 am, both on Sunday, at Offbeat (that's for the Eastern cruise). You are assigned to one of the two depending on your invite.
They have complimentary salsa, chips, and rum punches there, a short presentation about DVC, encouraging you to try the other collections, and a Disney/DVC trivia contest with prizes (coffee mugs, note pads, etc.)