According to SheridanHoops.com, Rajon Rondo is not the preliminary Olympic roster. Here are the point guards on the roster.
Follow that link for the full 19-man roster. As for Rondo… his withdrawal from the team last year might have been enough to remove him from the running on this roster. They have Williams and Paul as passers, so I'm sure they're not worried about having another distributor on the team. Don't be shocked if Westbrook and Billups don't ultimately make the team.
Rondo, for his part, is probably happy enough to be left off. I don't think he ever really wanted to be there in the first place.