Perhaps this article doesn't require any further elaboration than the headline, but I'm going to give it to you anyway. Here's the news:
Sweeney, Valbuena and Cabrera activated today for #Cubs . Sanchez DFA— Carrie Muskat (@CarrieMuskat) September 1, 2013
So Ryan Sweeney and Luis Valbuena are returning from injuries; the injury to Sweeney was particularly rough, because he was just starting to play well and would have clearly had a starting spot (left field) after the trades of Alfonso Soriano and David DeJesus.
Dale Sveum has already said he'll insert Valbuena into the starting lineup. For how long, we don't know.
I thought Eduardo Sanchez actually had a shot at making next year's bullpen; clearly, the Cubs thought otherwise, though if he clears waivers they'll probably keep him around for a NRI next spring. In the meantime, Alberto Cabrera will get some major-league bullpen time.
I wouldn't expect more than three or four more September recalls; the rest of them will be either when the Triple-A season ends after tomorrow, or possibly from Double-A whenever the Smokies are done with the Southern League playoffs.