Since 3.2, when otherworld have been fixed, there was no possibility to fly with flyingmounts in azeroth. But we will publish the new way hw to fly in azeroth soon.
From Jaburius KotS
This glitch allows you to fly in azeroth, As you know, the PTR allows you ride flying mounts without actually flying, what you dont know is, you can totally abuse it!
yeah mic messed up didn't feel like redoing, Step one go to dark portal, Step two mount flying mount walk through portal, step 3 shift to flgith form fly back, grats ...
During patch 4.0.3a, it was (is, for the moment) possible to die close to a Cataclysm-zone, run into the catazone, obtain the flying mount you get while you're ...