I've gotten exactly one. Funny thing about the day I got it...I really wanted one badly for my level 70 monk (still do). I played my monk for about 8 hours and found nothing good at all. I decided to switch it up and start playing my level 50 crusader. I kid you not, within 5 minutes of switching the very first chest I open, what do I get? Oh yeah, my very first (and only thus far) Thunderfury. I wish I had taken a screenshot of the orange light as soon as it dropped...I knew right away from the graphic what it was. Here it is in all its glory:
The sad part was, it wasn't even any good for my crusader, as he was already using a socketed level 70 dagger (level requirement reduced by 30) with about 2000 dps. So I put that ruby in it and gave it to my templar.
i had 5 fulminators, 4 flesh reapers, not a single tf, the only time i held the weapon was when a friend loaned me his freshly dropped to check if the proc scales with lightning skill % bonus (it does not btw)
No Shard of Hate, no Thunderfury, no Immortal King Set Item, no Andariels, no Thundergods, no Lut Socks, 3 badly rolled Earth Set Items so far.
A friend of mine has looted 5 or 6 TF until now... rng is so great -.-