Tata Martino is considering a move for Walter Samuel from Inter Milan. I've always rated Samuel as a top quality CB, underrated by many even. He's not nicknamed 'The Wall' for no reason, and Zanetti's described him as the hardest player he's ever played with.
35 years old now though, and has always struggled with knee injuries throughout his career. If Barca can keep him fit then he'd be a great asset, and a good option to share duties with Puyol as the man who plays alongside Pique.
I'm pretty sure that Milan stated earlier that they wanted to keep their vets, like Zanetti, Samuel, Cambiasso etc in the squad though, but they have parted ways with Dejan Stankovic (he'll be a decent signing for someone) and Ivan Cordoba.
It's just rumors at this point though, and they're only thinking about a move, so we'll see if something comes of that.