'change', 'update' events not firing for jQuery UI 1.6rc4 and jQuery 1.3b2

I'm using a slightly modified version of the UI Sortable Layout demo
and the 'change' and 'update' events for Sortable are not firing with
jQuery 1.3b2. Changing the script tag to point at jQuery 1.2.6 fixes
the problem. Is this a regression?