I changed ALL my passwords to random characters after Mt.Gox got hacked (had planned it for a long time, but never got around to it), before this I was using the about 3 passwords for everything.
I did exactly the same, I also wanted to do it all the time.
My MtGox password was different from any other fortunately except this very forum. But it has a little similarity with my standard passwords, so I fear that people might crack those more easily.