Quoting from the RSS 3.0 standard
The < language > Element
The < language > elements may be present under the < channel > element and also under the < item > element.
Good Stuff, its about time the language element was transferable down the RSS true. I'm a little upset
This feature is cascading. This means that when present beneath the < channel > element, all the channel's items are to consider having that language specification unless in those under which another < language > element is present, if any, in which case it overrides it.
Indeed, cool and very happy
When missing, this element's content is assumed to be “en”.
What the f*ck? This has to be a bad idea? Honestly why should the default be english?
For this purpose this elements may have one attribute, “rel”, whose content may be “meta”, “link” or “both”. This attribute is presumed to be “link” when missing. The content “meta” conveys the notion that the element is specifying the language of the metadata in the RSS document itself. The content “link” conveys the notion that the element is specifying the language in which the relevant content of the given link is written. The content “both” makes the two above mentioned interpretations equally relevant.
Now this is a good idea which I've seen used in the microformats and XHTML 2.0 areas.
This item's content must be compliant with the RFC 1766, “Tags For The Identification of Languages”. This means that the content of this tag is two letters representing a language (as defined in the ISO 639) which may be followed, after a dash, by two more letters signifying a particular country (as defined in the ISO 3166).
Implementors should only acknowledge the first letters until the dash, if any (presumably two), though if the specific country is relevant it may regard the country specification. Thus if the element's content is “en-US” it is to be considered as “English”, and may choose to regard or disregard the country specification.
Hummm… I really dont like the way, english labeled content is being singled out above other languages. Indeed its worrying and that just the language element…