SATURDAY 12:13pm: The Pirates want a "Chapman-type deal" for Melancon, Jon Heyman tweets. They aren't very likely to get one, but in the current market, I suppose it doesn't hurt to at least see what's out there.
FRIDAY 6:38pm: The Giants and Indians are also interested in Melancon, Rosenthal tweets. The Pirates want a late-inning reliever -- although not necessarily a closer -- as part of the return in any trade, along with prospects. That sort of makes sense, in that the Pirates would presumably see a Melancon trade not primarily as an excuse to build for the future but as a way to capitalize on Melancon's value as a closer without significantly weakening their current team.
12:59pm: The Nationals are in discussions with the Pirates regarding a potential deal for Mark Melancon, Ken Rosenthal tweets. Rosenthal notes that other teams are also interested in Melancon, although he doesn't name them.
There's no harm in listening to offers, but as I noted yesterday, I don't think trading a very good closer in the midst of a pennant race is generally the sort of thing the Pirates should be doing. Perhaps there's a way for the Pirates and Nats to swing a deal such that the Pirates get someone back who could help immediately, in which case it might be fine. Trea Turner, who's currently a backup for the Nats, could help the Bucs right away, although dealing Turner for Melancon would be a massive overpay on the Nationals' part. Perhaps a starting pitcher like A.J. Cole (a good, but not great, prospect who could immediately join the Pirates' rotation) might also make sense.
In general, though, I would be surprised if the Pirates traded Melancon, as he's unlikely to land the sort of return elite relievers like Aroldis Chapman and Craig Kimbrel have recently commanded, and the Bucs are within reach of a playoff spot. Melancon, of course, is eligible for free agency after the season, but I think the Pirates might just have to accept that at this point.