Assuming the Pirates are done here (and occasionally you'll get a deal that's announced an hour or so after the deadline, which was at 4:00), what they've done at the trade deadline is to acquire Derrek Lee and Ryan Ludwick for Aaron Baker and a PTBNL or cash. They've DFAed Mike Crotta to clear space for Ludwick on the 40-man roster.
Given the prices some teams were paying for star players, what they did makes a lot of sense to me. I'm not exactly jumping for joy, but this is pretty much what I thought they do. Assuming the PTBNL is no one of value (and they usually aren't), the Pirates have given up very little to get two players who are upgrades on Lyle Overbay and Matt Diaz. (It's kind of funny that the Bucs' two moves at the deadline basically correct two mistakes they made in the offseason.)
Neither Lee nor Ludwick are world-beaters, but they're both functional. Ludwick will likely play most days until Jose Tabata and/or Alex Presley get back, then move into a part-time role where he starts against righties, pinch-hits, and plays as a defensive sub. He's not a good offensive player anymore, but his defense still keeps him well above replacement level, and I do think moving from PETCO will help him. He should also be a Type B free agent after the season.
People are going to be upset about this, in that the Pirates didn't acquire any stars, but they upgraded two roster spots and didn't give up much of anything except money. As the market unfolded, it became clear that the Pirates shouldn't be in the market for stars, because they were way too expensive. Lee and Ludwick could well flame out, but I think they were chances worth taking given market conditions.