The <time> element
The WHATWG Web Applications 1.0 Working Draft defines a time element, which is intended to contain a date and/or a time in an international date, formatted in a way that is only a slight superset of RFC 3339.
I can imagine how in the future that can be handy for spiders and for rendering localized or accessible content in the future, but for now the best that can be done is to emulate some of that via JavaScript.
I’m trying it out on my weblog. Previously, dates were displayed in EST/EDT, but now they are initially displayed in GMT/UTC, and subsequently localized to your local preferences.
I’m not aware of anybody elese doing similar things, with or without the use of the <time> element. If anybody knows of any such uses, or even other deployed applications of the <time> element, I’d appreciate it if you left a pointer in the comments.