I just read this. Anyone with a level 80 will be able to get cold weather flying at level 68 using an heirloon item bought for 1000g. If you have the gold you will be able to level through northrend with epic flyers.

Just to confirm, Tome of Cold Weather Flight is actually a new heirloom item planned to go into patch 3.2. At level 80 players can buy this heirloom item from the Cold Weather Flying Trainer in Dalaran for 1,000 gold and send it to an alt of the same realm, faction and account. The tome can be used to learn Cold Weather Flying at level 68, consuming the tome in the process.

Please note this feature is not yet in the newest version of the public test realm patch notes updated today. The item and its functionality are subject to change during the testing process.