The Palm Beach Post reports that Manning is actually the teams #1 priority if he ends up being available. The Dolphins would still be interested in signing Packers QB Matt Flynn depending on what happens with Manning. You can expect to see some amount of interest from teams like the Redskins, Jets, and possibly the Cardinals.
This is not all that surprising as Dolphins owner Stephen Ross has said publically that finding a new quarterback will be one of the teams top priorities during the offseason. It should be interesting to see how aggressive they are once free agency is open for business.