After 1 Blood Seeker 16 hours of camping I was pretty bored and wanted to make a quick circle around deepholm to check for possible corpse etc. and I found Aeonaxx! My hands were shaking because it was so far away and if I was just 1-2 second slower I would have not gotten it.
Good luck for everyone and I feel very sorry for couple of people who had been camping it for months and missed it many times. :'(
Here is a screenie I almost forgot to take:
If no one noted, Aeonaxx starts as a friendly NPC that has a vehicle arrow on mouseover. It isn't until you mount him that you are able to attack and kill him (and get your sweet Reins of the Phosphorescent Stone Drake mount)
Drops the Reins of the Phosphorescent Stone Drake, a rare purple stone drake mount.
Aeonaxx has the chance of spawning every 6-22 hours.