Date and Time Picker recommendation

What would you recommend for a Date and Time Picker?

Something like this would be nice:
http://37signals.com/svn/posts/887-design-decisions-calendar-picker-for-backpack-reminders

I've used jQuery but I notice lots of RoR coders like to use Prototype.

i used this:
http://jqueryui.com/demos/datepicker/

about jquery…
use jquery OR prototype for prevent problems.