If you go to Users->Your Profile, you can turn off the Visual Editor. You’re limited to writing your posts in HTML, which is definitely not optimal, but the damn WYSIWYG editor won’t strip out your formatting anymore.
I’d really, really like to see this fixed, wherever it needs to be (sick of reading flame wars back and forth about who’s at fault) since starting up Firefox everytime I want to post, when I’ve already got Safari open is a PITA.