<p dir="auto">Main page - <a href="http://twitter.github.com/bootstrap/">http://twitter.github.com/bootstrap/</a>, pressing the big "Download Bootstrap" gives you everything.</p>
<p dir="auto">Going to customize - <a href="http://twitter.github.com/bootstrap/download.html">http://twitter.github.com/bootstrap/download.html</a> (specifically Responsive layouts)</p>
<p dir="auto">Having everything checked, scrolling to the bottom, and downloading - doesn't give you bootstrap-responsive.css</p>
<p dir="auto">Wondering why all my menus were going nuts.  Thanks!</p>
<p dir="auto">The default download has the responsive and non-responsive as separate files, but the customizer combines them into a single file. They should have the same file structure, so the customize should give you the responsive layouts in a separate bootstrap-responsive.css.  Will make it less confusing as to whether you have a bootstrap file that has responsive layouts or not.</p>