Tim has a good piece on Pirates' fans interest in Reds first baseman Yonder Alonso. The gist of it is that the Reds might not trade Alonso within the division anyway, are unlikely to trade him for Joel Hanrahan, and may want more for Alonso than he's actually worth.
I like Alonso and I think he'd be a very good fit for the Bucs, but I think Tim is right on. I would probably trade Hanrahan for him, but I'm not sure the Reds would be willing to trade a guy who might beat them in N.L. Central games for years to come, particularly when they reportedly aren't interested in dealing him for Andrew Bailey of the A's. And even then you could make the argument that the Pirates shouldn't do the deal, since the Pirates should be trying to hit a home-run ball in a Hanrahan trade, and Alonso looks like a double at best.
For the same reason, the Pirates can't really trade anything more than Hanrahan, because Alonso projects as a good player, but not a star. The .330/.398/.545 line he posted in a small sample in the majors last year looks like a mirage. He doesn't have outstanding power for a first baseman, and he isn't particularly young, so one would hope he'd be a bit further along in developing it. He does hit for a bit of average and control the strike zone well, but that makes him like ... Casey Kotchman in Kotchman's good years, or maybe the first few years of Lyle Overbay's career. Baseball Prospectus actually lists Adrian Gonzalez as Alonso's top comparable, which I suppose is one possible outcome, but I think it's only a remote possibility. Tim compares Alonso to Adam LaRoche, which isn't quite a match in terms of his skill set, but is a pretty good approximation of his value.
Basically, I think Alonso looks like he should be a couple wins above replacement most years. That means he does have significant value, especially since he'll be cheap for the first few seasons. But it's not worth selling the farm for.