When I ported my Phonegap code over to using Zepto instead of jQuery, I struggled the most with porting the jQuery tools DateInput plugin. I eventually got it to work, but man, it required a lot of little hacks and just didn't feel so great. I ran with it for a little bit, but then decided to see if there was a better alternative standalone datepicker, and I found this pull request to Twitter Bootstrap for a input-triggered datepicker. I took the code attached to the request and modified it to be standalone, and it totally worked, both with Zepto and jQuery. Here's what it looks like:
You can play with a demo of my modified standalone version here. That demo also shows using the date.format.js library for pretty printing the date. If you want to use it yourself, you can grab the JS/CSS from that demo, or the JS from this gist and the SaSS from this gist. Or if you don't need a standalone version, check out the demo for the original datepicker and grab his code from the pull request.
Hopefully the datepicker gets pulled into Bootstrap and becomes an official plugin. It's something that many websites need and the HTML5
input type="data" isn't giving us what we need yet, not even in the modern browsers.