Same thing happened to me. Very stupid of me. I caught the MtGox news a bit too late. By the time I had checked, the BTC I had with MyBitCoin had already disappeared!
I have since then changed my passwords on almost any site I can think of to something considerably more secure (and varied for each account/usage).
Thankfully I only lost 2.6 BTC. Sadly, that's still a good chunk of change for me right now. I do believe most of that was made through mining, so it's not a total loss.
Anyone willing to help a moron recover some of his lost BTC with some donations?

In the extremely unlikely chance that you are, PM me!
I'm changing all my passwords to... things like ' 5%[">s)Lv[tb{