" July 2014 (UTC)
I didn't say that the summary= attribute is not working; I said that it was marked as obsolete. Obsolete in this instance means that browsers claiming compliance with HTML 5 need not support it, and people writing pages that claim compliance with HTML 5 should not use it. But most browsers that support HTML 5 also support HTML 4, not just because it will take a long time for everybody with a website to rewrite the content for HTML 5 (if it ever happens: there are still a lot of HTML 2.0 or 3.2 compliant pages out there that would fail a conformance check for HTML 4, let alone HTML 5), but also because HTML 5 has not yet reached the W3C Recommendation stage, so the current stable standard is HTML 4.01.
On some discussion pages (I know of at least three threads outside of User talk: space) there is a scaremonger going around telling people to stop using the  element ASAP, because it's marked as obsolete in HTML 5. Don't panic: it still works in every browser I've tried it in though, and will probably do so for a long time yet.   07:42, 28"