The recent updates to DatePicker are flawed in a few ways.

The new $.fn.datepicker function is calling deprecated functions by using:

this[option + 'DatePicker'].call(this, args)

Unfortunately, that doesn't work for getDate and SetDate since the functions there are

$.fn.getDatepickerDate

$.fn.setDatepickerDate

clearly this doesn't fit with the model.

Secondly, implementing the new API by calling out to the old, deprecated API is a very bad idea. Its going to make it that much more difficult to retire the old interface. The implementations should all be internal to $.fn.datepicker and the old API should call it.

You can test this by taking the demo that comes with the jQuery UI bundle and simply calling .datepicker("getDate');