[Kri0-Gen]

Таки запилил решение на событиях ui-datepicker.
Если кому понадобится, вот код:

$(<селектор>).datepicker({ showButtonPanel: true, closeText: 'Выбрать',
					onSelect: function (dateText, dp) {
						$(this).datepicker('setDate', dateText);
						dp.show(); 
					},
					onChangeMonthYear: function (year, month, dp) {
						dp.currentMonth = month;
						dp.currentYear = year;
						var maxDay = 31;
						if (dp.currentDay > 28) {
							if (month == 2 && (year % 4 == 0 && year % 100 != 0 || year % 400 == 0))
								maxDay = 29;
							else {
								var daysInMonth = [31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31];
								maxDay = daysInMonth[month - 1];
							}
							if (dp.currentDay > maxDay)
								dp.currentDay = maxDay.toString();
						}
						var dateStr = "";
						dateStr += dp.currentDay < 10 ? "0" + dp.currentDay : dp.currentDay;
						dateStr += ".";
						dateStr += month < 10 ? "0" + month : month;
						dateStr += "." + year;
						$(this).datepicker('setDate', dateStr);
						$(this).val(dateStr);
					}
				});