Confirmed in http://hg.mozilla.org/mozilla-central/rev/ba4983d9c1f9 Mozilla/5.0 (Windows NT 6.1; WOW64; rv:14.0) Gecko/20120326 Firefox/14.0a1 ID:20120326031149
Mozilla/5.0 (X11; Linux x86_64; rv:13.0) Gecko/20120315 Firefox/13.0a2 Setting to new. Loading the bookmarked URL in new tab doesn't work in F13 Aurora.
Happens in Win7 + Firefox 13.0.1
Yup, happening here too (Mageia Linux 64bit 13.0.1). I thought it was broken generally, but I now see it's only on the new tab page with the fancy common sites thingy. I have a few js bookmarks, some for keyword searches for sites where simple %s replacements are not enough, where this can get quite annoying as it's typically on the new tab page where I use these.