Nothing like a William Blake reference to start off a post about Warcraft.
Fandral's Flamescythe, dropped by Majordomo Staghelm in the Firelands raid, transforms a druid's cat form into a burning awesome Druid of the Flame!
The only way for another class to get this form is to use a Potion of Illusion while targetting a druid in burning kitty form.
All in all, I think the item should have an on use effect to grant anyone the fiery coat, even if not the full Flame Cat effect. But it's still pretty cool.
Expect to see this getting farmed into oblivion within the first few patches of Mists of Pandaria, as Firelands becomes old content. Farmed by armies of druids. There will be arguing. Oh yes... Druid arguments are always fun.