If you do what I said, it all does go in the same line. The problem is that each of those modules is trying to be horizontal, and there's simply not enough space. By placing the span3 and span6 on things, that makes them all go in one line, but the login module has to wrap as there's no way to do it otherwise. Right now, without designating what should wrap, the browser is simply trying to keep them all as wide as they want to be, and doing so prevents them from all being on the same line.
I did test the suggestions I made above using Chrome's debug tools and they were all on one line.. but with some wrapping. You'll just have to determine what should wrap.
I hope that explains,
Alex