As has been mentioned, Mike Rivera cleared waivers and accepted an assignment to Nashville; Grant Balfour also cleared but is deciding whether to accept or become a free agent.
Also, per Brewerfan.net, the Brewers signed Joe Dillon to essentially play Vinny Rottino's utility role at Nashville. As Mass Haas points out, that portends well for Vinny's Major League chances, especially coupled with this quote:
Coming off his outstanding 2006 season, outfielder Tony Gwynn is currently in contention for a bench spot with the Milwaukee Brewers, though he figures to begin the season in Nashville.
By the way, Joe Dillon is pretty good.