No, it's not easy, but it is possible now that reputation rewards for quests don't degrade with level. However, questing alone doesn't seem to be enough to get a mount by 40, as explained by goffchick on wow_ladies. The real trick seems to be timing it so you can run (pre-60, it's more likely to be corpse-hop) to as many lunar festival elders as possible. (Yes, for each elder you speak with, you gain 75 reputation for all horde or all alliance factions, depending on your faction, of course.) Anyone else out here who's managed to snag a cross-faction mount at or around level 40? I'd be curious to hear how difficult it was.