While getting your character(s) to eighty is obviously a focus with the new expansion, another grind to keep in mind is the faction grind. There have been some major changes to the faction grind in Wrath of the Lich King.

Let's get the important news in first. Quoted from World of Warcraft.com:

Northrend Special Reputation Tabards:

If you're friendly with certain Northrend dungeon factions (Wyrmrest Accord, Knights of the Ebon Blade, Kirin Tor and Argent Crusade only), you can wear that faction's tabard to any level 80 dungeon and funnel all the rep to that faction. Make sure you pick up your tabard as soon as you can!

Raising faction is much more enjoyable than in the past. Now you can run any level 80 or heroic dungeon and accrue the reputation of your choice....as long as your choice is one of the four factions that have tabards. Tabards can be purchased once your reputation with that faction reaches Friendly. Additionally, running the regular dungeon daily results in the award of a token good for faction rep with one of the four tabard factions. Just choose the faction you wish to focus on and faction gains should fly compared with past reputation grinds. I still suffer the occasional Naga nightmare after grinding my way to Exalted with the Sporeggar.