The WN server does it using a table, so they parse the document only once a day. Ok, it isn't the best way, but there are many ways to resolve it. In fact it'd be good if robots started to promote this. I've made some alterations to that draft, to be clearer and more exhaustive. You can find the draft here.
Suggestions are welcome.
The aim of this Draft is to define which are the words to use to define the contents of an HTML document. The META element is used within the HEAD element to embed documents meta-information not defined by other HTML elements. Although it is generally preferable to used named elements that have well defined semantics for each type of meta-information, such as title, this element is provided for situations where strict SGML parsing is necessary and the local DTD is not extensible. This attribute binds the element to an HTTP response header. If the semantics of the HTTP response header named by this attribute is known, then the contents can be processed based on a well defined syntactic mapping, whether or not the DTD includes anything about it.