The HTML5 input types are great, Opera\'s new built-in date picker is a breeze, and Chrome has at least supported the new input type with a spin-wheel implementation.
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Since there's no default method of setting the value to today's date, I would say this should be dependent upon it's application. If you're looking to maximize your audience's exposure to the date picker, then use a server-side script (PHP, ASP, etc.) to set the default value.
However, if it's for the administration console of the CMS, and you know that the user will always have JS on or your site trusted, then you can safely use JS to fill the default value, as per jlbruno.