Unfortunately the code:
does not work that well. IE7, IE8 produce NaN, and FireFox produces "Invalid Date".
What I use instead (and what is supported as of IE9 and all the other modern browsers), is the ISO-8601 non-zero based format:
And then I add a Date contructor polyfill for IE7, IE8.
Still, the Kendo UI date formats "u" and "s" are misleading. They use the Z for zero-based UTC, but produce a non-zero based one.
For now, I will try the UserVoice website. Once I get the commercial license, I will use a support ticket ;-)