Hello, this happened three days ago. My password was very strong and never compromised. I would love to know myself how my account was hijacked. I've continued to ask support for help, but they are doing nothing, other than restoring my original email. There were several withdrawals on my account, all done within minutes, the largest withdrawal was 258btc. The problem I have is that the hijackers was able to use my $ to buy bitcoins with several transactions, and make several withdrawals, all without confirmation from me and within 20 minutes total. MtGox has destroyed the BTC market, and I feel they will continue to compromise the overall market for BTC.
Unless you boot your computer freshly from a live CD or have just barely installed an OS, the moment anyone starts browsing the internet at large, there is no way they can be certain they don't have a keylogger on their machine. Bitcoin is known to malware authors, and they will target bitcoin-related passwords. If you get keylogged, you will never have any way to prove or disprove that that's what happened. Likewise, MtGox isn't going to be able to either - the only thing they can do is say that somebody from IP address x.x.x.x logged in and withdrew your funds to address X.
This is why I have a Yubikey. I am conscientious and practice safe computing habits, but you never know when you're going to get compromised by the next "0-day" vulnerability. Safe computing means assuming your computer is probably compromised all of the time and planning accordingly to reduce your risk. (For example, not only do I use Yubikey, the computer I use to log in to MtGox and transacting Bitcoins is absolutely NEVER used for surfing the web, because I believe a computer not used for web surfing is far less likely to be compromised).
The Yubikey is far from perfect - but it is pretty effective against keyloggers and makes you a far more challenging target for hackers. It is also pretty powerful because the physical key has two modes, one for generating login passwords and one for generating withdrawal passwords. A Yubikey code generated for a login won't work for a withdrawal, so even if somebody breaks into your account, they can't do anything with it (other than trade) without a code they're far less likely to have a chance at getting.