What you did is no different than what Lulzsec has been doing this past 50 days - blatantly disregarding the safety of individuals in order to make a point, arrogantly.
You say that like it's a bad thing?
You NEVER release 0-day exploits into the wild without a LENGTHY process of notification to the original coder
Maybe YOU don't. Plenty of people do.
There's an email feature in the mtgox interface where you can report bugs without exposing innocent traders (who will be affected by exploits if the price swings or if one of your 0-days can lead to compromising other people's balances or wallets).
Not my problem. If you're so worried about this particular scenario maybe you should be lobbying the bitcoin vendors you use to open their systems or publicly disclose results of code/security audits, etc.
I can agree on full disclosure for big bureaucratic organisations that ignore you when you report a bug.
But honestly, in this case, for a small company like MtGox.
A small company with a proven track record of ignoring such reports is no better than a large company full of Kafka-esque nightmare-level bureaucracies.