Hi Micha, I am seeking the same information and would be keen to hear any solutions on this. I noticed BC Gurus have a twitter bootstrap template which I plan to install within the next couple of days to hopefully work out how they did the navigation. I did however notice that their drop down menu was a little different from the standard bootstrap one that requires you to click the top level nav in order to display the drop down. I'm not fussed whether it clicks or not, just after a menu that is responsive and works within bootstrap that is easily styled with css. Let us know how you go too.
I think I managed to use Bootstrap with the dynamic menu here:
I think it's just a matter of applying BC menu ID into bootstrap's CSS.
I'll give it another go. I tend to get stuck with the double/hover 2 level navigation. Much appreciated.