Ken Rosenthal reports that the Pirates have "two high-level scouts" at tonight's David Price / Jon Lester matchup in Tampa.
Not to be a broken record here, but I wouldn't believe the Pirates will trade for someone of Price or Lester's caliber until I saw it. Lester is a rental and Price is going to be very expensive next year before becoming a free agent after 2015, and I'm doubtful the Pirates will trade top prospects for rental players. There's also the possibility that the Pirates' scouts are at the Trop primarily to watch players other than Price or Lester. The Red Sox have several relievers who could be useful, for example. Price and Lester are great, but you're probably just going to end up disappointed if you think too hard about this. If you find yourself getting excited, think back to the Pirates' somnambulant offseason. Flashy isn't their style, at least not where veteran acquisitions are concerned.
UPDATE: I should add that, as far as I know, the Red Sox still want to sign Lester to an extension. It would obviously still be possible for them to re-sign him if they traded him, but it's less likely, because they won't have the exclusive negotiating window and because players often take being traded as a cue to move on. (I forget where I read this, but apparently many players do think this way.) There's also the fact that, with a trade, the Red Sox would relinquish the leveraging power of a qualifying offer (and the possibility of an accompanying draft pick). I doubt they'll deal him unless they get something really good.