Right, I know very little about BTC (I own a glorious 10 lol), but I know my stuff when it comes to websites (14 years experience, CTO).
Let me tell you that there's going to be drama all around when the market starts dipping. Today Bitstamp is taking 15 seconds to load on my account page and there's barely any visits to that site compared to MTGOX.
In the realworld, yes the exchanges can crash, but that's incredibly rare, and these things are built with redundancy in mind and are load tested to the hilt. Even when they take a nose dive, the operators have clones ready to get online. I mean I've visited some of the ones in London, and we're talking acres of server rooms, the best of the best connectivity, the best of the best hardware, dedicated fiber they've dug themselves, triple redundancy.
As far as I can tell none of the BTC exchanges publish what and how they host their websites, and if looks are an indication of the code quality (which more often than not it is), then we're going to be up s**t creek with no paddle as we panic to try and sell our coins only to be greeted by 503 server unavailable errors.
Just sayin'.
Welcome to the still relatively "amateur" world of bitcoin. I'm sure this still will start to improve as it becomes more and more worth the investment to have better services and redundancy. Just in the 7 months i've been in the 'scene' the level of professional services and companies getting involved in the ecosystem is greatly increasing.