No chance this happens. The Rockies aren't going to trade two of their best players, especially one like Helton who is having a comeback season and is the face of the franchise, for anything the Yankees would offer. I'm not sure why these Helton trade rumors are re-surfacing themselves now, but I see no possible way the Rockies will trade Todd this season. The offseason is another matter, but if Todd continues at this pace I doubt he'd be traded at all.
As for Fuentes, I agree with Yoda that it's very possible he'll be dealt at the trade deadline. He'll be a free agent after the season, and his market value should be quite high. With Manny Corpas performing very well in the setup role, there's already an in-house candidate to take over for Fuentes if he is dealt. Hopefully he isn't traded, but I think there's a possibility he will be.