Moms were all the rage this weekend in the Thirty Mile Zone -- and while Kim K shook her ass for hers at the Pussycat Doll Lounge in Vegas, Reese Witherspoon only wanted to know how our photog's mama was doin'.

Also -- John Mayer made it abundantly clear he broke up with Jen Aniston -- not the other way around -- and Mr. Olympia proved his gigantic size may be overcompensation for his tiny voice.