Worked on the jQuery Datepicker with time feature in Apex 4.0. One of the interesting addition is adding Time picking functionality with the jQuery Date Picker. Apex 4.0 have better Date Picker with various options which otherwise not possible with old date picker.
Options like year selection, month selection, multiple month display, internationalization, minimum date, maximum date restriction etc and very handy features.
Overall i can say the new jquery Date Picker gels well with Oracle application Express 4.0
Try out the feature others with apex.oracle.com, now running with Apex 4.0