According to Danny Knobler of CBS Sports, Texas offered coveted third base prospect Mike Olt to Atlanta for shortstop Andrelton Simmons, who impressed everyone as a rookie this past season with both his glove and bat.
The Braves said no.
The thought process behind the deal for the Rangers was they would then flip Simmons (or one of their in-house shortstops) to the Arizona Diamondbacks to acquire outfielder Justin Upton. In exchange for Simmons, the Braves could potentially have a slugging third baseman in Olt that would help smooth the transition following Chipper Jones' retirement.
Teams in Major League Baseball seldom deal two young players as talented as Olt and Simmons. That's what makes the prospects of this one-for-one "trade rumor" so interesting.
Simmons is already (arguably) the best defensive shortstop in baseball and should be a pretty solid contact hitter. Olt established himself as one of the game's best offensive prospects after hitting .288/.398/.579 with 28 home runs at Double-A this season.
It seems there's nothing more to this deal, although the Braves would likely be very interested in Olt if Texas became enamored with any their many pitching prospects. This is pure speculation though, and we can probably put this fun little rumor to bed.