...
I presume we will need to run this pass the Incubation sponsors to see if this concept will fly.
JS Calendar Replacements
YUI Calendar
One contender is YUI Calendar http://developer.yahoo.com/yui/calendar/ which has a BSD license.
This widget unfortunately has quite large dependencies 250KB.
The Interval Selection calendar is quite impressive. http://developer.yahoo.com/yui/examples/calendar/intervalcal.html
There appears to be no time support.
jQuery DatePicker
Another contender is jQuery DatePicker http://jqueryui.com/demos/datepicker/ which has a MIT and LGPL license.
The restrict date range looks very handy, there are lots of display options, including multiple month displays
This widget unfortunately has quite large dependencies 155.58 kb, minimised
There appears to be no time support.