It would be sad to see Clement go, but at least it's the Red Sox, so I can still root for him.
Personally, I wouldn't make the trade, but if the team has already decided that Maddux would be our #4 playoff starter (assuming the others are healthy), and that we wouldn't resign Clement, then it's an ok trade.
Our lineup would be massively improved with Nomar. It allows us to move Patterson from the 2 spot (.266) to the 7th spot (.319), where he fits much better. And we'll finally have a decent top of the order with Walker/Grudz and Nomar. Although, knowing Dusty, he'll probably bat Nomar third or something.
Looking at the new posts, I don't like the Cabrera trade at all, unless it helps us get Nomar without giving up Clement. Beltran has nasty stuff, and he's going to be great in a few years when he lowers his walk total.