Full disclosure: I am guilty of starting this rumor.
The Denver Broncos will / should trade their two first round picks (numbers 12 and 18) to the Seattle Seahawks in exchange for the 4th overall pick. I know it's not a perfect match on the NFL Draft Value Chart, but it's a perfect match of needs.
Why Denver will / should do this: The Broncos would virtually guarantee themselves one of the top two quarterbacks in the draft, either Matthew Stafford or Mark Sanchez. In essence, they would have traded their own first and fifth round picks and Jay Cutler for either Stafford or Sanchez, Kyle Orton, a third rounder, and a first round pick next year. Seems pretty fair especially since Cutler and new head coach Josh McDaniels did not see eye-to-eye anyway.
Why Seattle will / should do this: Seattle has many pressing needs. Trading down would allow them to take two impact players. In a perfect scenario for them, they would take a safety (possibly Malcolm Jenkins) with the 12th pick and a quarterback of the future (possibly Josh Freeman) with the 18th pick. Strategically, in order to get Freeman, teams will have to trade ahead of the Tampa Bay Bucs who happen to pick 19th.