lexipixel - 12:59 am on Jun 2, 2012 (gmt 0)
..and now it's back.
I called support there -- nice to talk to a human. He had me clear cookies and cache, log out, then log back in -- it's seems I was (unknowingly) part of a UI test group.
The searchbox and related controls had what I'd call an "Ajax feel"... the search box had that soft-greyish js framework look and feel to it, (unlike a standard HTML text input), and had a 6-toothed gear icon that toggled a pull-down that took you into Advanced Search.