Originally came out about 3 months before WotLK. It let you and your friend teleport to each other once every 30 minutes, gave 300% xp when grouped together (up to level 60), and let your friend grant you 1 level for every 2 that they gained. After they were subbed for 2 months, you’d get a free month, and after 3 you’d get a mount (Originally the Zhevra, then the X-53 rocket).
We’re one week away from pre-patch and just over a month away from launch, and Blizzard hasn’t given any info about if/how this will be implemented into the game, or if not, how we’ll be able to acquire those mounts
There’s still 2 unique mounts tied to it, one being the only 2 person flying mount until Cataclysm (vial of the sands from Alchemy).
And it would be nice to be able to bring a friend to the game, and have at least part of the leveling be faster. If multiboxers are abusing it, then they should properly enforce their ToS, not remove a feature that was in 100% of WotLK.