Hmmm suppose you're right, it appears they want to release-candidate the release-candidate by having people run the 1.4 branch. We'll see what happens to the blockers.
Of course, they could always demote them to "critical". The following should list all the critical AND blockers still in the system with targets of 1.4 or earlier (why some bugs have targets for old versions of Mozilla, I don't understand):
http://bugzilla.mozilla.org/buglist.cgi?query_format=&short_desc_type=allwordssubstr&short_desc=&target_milestone=mozilla1.1beta&target_milestone=mozilla1.2alpha&target_milestone=mozilla1.1&target_milestone=mozilla1.2&target_milestone=mozilla1.3&target_milestone=mozilla1.4&target_milestone=mozilla1.1final&target_milestone=mozilla1.2final&target_milestone=mozilla1.3alpha&target_milestone=mozilla1.3beta&target_milestone=mozilla1.3final&target_milestone=mozilla1.4alpha&target_milestone=mozilla1.4beta&target_milestone=mozilla1.4final&long_desc_type=substring&long_desc=&bug_file_loc_type=allwordssubstr&bug_file_loc=&status_whiteboard_type=allwordssubstr&status_whiteboard=&keywords_type=allwords&keywords=&bug_status=NEW&bug_status=ASSIGNED&bug_status=REOPENED&bug_severity=blocker&bug_severity=critical&emailassigned_to1=1&emailtype1=exact&email1=&emailassigned_to2=1&emailreporter2=1&emailqa_contact2=1&emailtype2=exact&email2=&bugidtype=include&bug_id=&votes=&changedin=&chfieldfrom=&chfieldto=Now&chfieldvalue=&cmdtype=doit&order=Bug+Number&field0-0-0=noop&type0-0-0=noop&value0-0-0=
Oh well. Still looking forward to 1.4, regardless!