That pretty much says the whole story right there -- but since when have I let that stop me? Our old friend Cold Weather Flying is seeing a significant price drop in Cataclysm, it seems. In addition, the level at which you can get it is changing. On the live servers, you currently can buy Cold Weather Flying at level 77 (or level 80 to buy a Tome of Cold Weather Flying). The tome is Bind to Account and allows an alt to learn CWF at level 68.

In Cataclysm, all of this is unnecessary. You hit level 68, you spend around 500g (475g for the human character I used to test this, talking to a flight trainer in Stormwind) -- and bam, you can fly in Northrend. (Said human was level 1; as you can see, he didn't even have 1 solitary copper on him.) So there you go. Do all of your alts have CWF? If you somehow have an alt who is above level 77 but doesn't have it yet, will you be picking it up?