A few hours ago, Jon Heyman reported that the Brewers are showing interest in reacquiring Francisco Rodriguez. With the bullpen struggling, reacquiring him would be a step towards trying to improve a bullpen that has struggled over the first week and a half of the season. The Brewers bullpen ERA currently sits at 6.11, which is 27th in MLB. It's not clear if an offer has been made yet, though Heyman mentions a few other sources that say a deal could be close.
In addition to the Brewers, the Angels and Marlins are also showing interest in Francisco Rodriguez. Both have also had some bullpen struggles this season, and are looking to help improve their bullpen as well.
The Brewers originally acquired Rodriguez at the All-Star break in 2011, and he helped the Brewers make a run into the playoffs that year, posting a 1.86 ERA in 31 appearances. He accepted an arbitration offer with the Brewers after that season, though his 2012 season was much rougher as he posted a 4.38 ERA in 78 appearances. He did not sign with anyone in the offseason, but did pitch in the WBC for Venezuela.