Unlike either of those zones, however, the FPs in Icecrown are extensively phased. Only two of them, Argent Vanguard and Death's Rise, are accessible immediately upon entering the zone, so don't go cruising around trying to pick up all the FPs. Just go through the normal quest lines and you'll unlock all four of them sooner or later.
Argent Vanguard. This one is open straight off the bat, and the quests from here (and from your faction's airship) will lead you through the zone. Aeden Moran (88,78) is the flight master.
Crusader's Pinnacle. More of a stepping stone, I don't remember there being a lot connected to this place, but it's there anyway. Opened by the quests from Vanguard. It pleases Penumbrius (80,72) to offer flights from here, and on nice green drakes no less.
The Shadow Vault. This one is really cool. I don't want to spoil too much, but there is some very nice questing surrounding this place. Morlia Doomwing (44,25) handles the flights.
Death's Rise. This is just a ledge in the side of the cliff, which looks out over the Scarlet stronghold Onslaught Harbor. Most of the quests out of here are connected with the Onslaught, and it takes some breadcrumb quests to open most of the NPCs here. Dreadwind (19,48), however, will fly you around any time (thanks for the corrections).
That's all the zones! Nothing now remains in my flight path series but a post on Northrend as a whole (which is coming). Previously: Lower Northrend (Alliance/Horde), Grizzly Hills, Zul'Drak, Sholazar Basin, Storm Peaks.
Arthas awaits and so do your questions. Find the answers you've been looking for that will help you with your journey into Northrend and to level 80 with Wrath 101.