Blizzard historically makes it very difficult to obtain mounts that are traditionally used by the opposing faction, unless you happen to be a Horde character who was around for the inaugural Brewfest. You're typically looking at a 1% drop rate, and sometimes a lockout of a day or longer on repeating the instances in question. Also, if you need help to beat the bosses in question, you're in for a roll-off if it finally drops. Going for these mounts is something to do for fun and/or out of boredom, but not because you seriously think you're going to get one.
Thanks to insane gear inflation in Wrath, I've been curious to see whether I could SOLO bosses from previous expansions who drop shiny mount rewards. Over the weekend, I learned to take down the 5-man heroic Magister's Terrace, where Kael'thas has a chance of dropping a white Blood Elf chicken. It takes me the better part of an hour to make the run, but it's actually challenging, so I enjoy the effort.
With that out of the way, the next question was the level 60 Zul'Gurub 20-man raid. I ran this place into the ground at level 60, and never even saw the Raptor boss drop the Troll raptor mount. However, I read that the fight was soloable, so off I went to ZG. It turns out that yes, the raptor boss can be soloed by a mage. He has a habit of stopping to whirlwind and generally running slowly, so you can kite him around the instance until your cooldowns are ready, pop the water elemental and mirror images, and do a bit of damage. It took over 17 minutes, but I was able to kill the guy.
Wait a minute.... what the heck is that second item that dropped?!
This was the mount that I've always wanted the most, but I hadn't even considered that I'd ever actually get to own it if for no other reason than because of the 3-day raid lockout. I even farmed up the rep on my Tauren because I figured that would be as close as I'd ever get. Some days, the RNG decides to smile on you, I suppose. I'm not sure if this technically counts as having dropped on the first try, since I have killed that boss a few dozen times in raids, but I'll take it.
(P.S. Of course, we would have major breaking LOTRO news come up literally as I was taking my celebratory screenshots. Go ahead, Turbine, take the spotlight, really. ;))