Help:Interwiki linking on Wikimedia wikis
You can link to encyclopedia pages on the various language wikipedias using links in the same form as the interlanguage links. Unlike there, they will appear here inline in the text. 'w' is an alias for the English wikipedia (also 'en') for historical reasons.
To link from them (those running the new software, that is) to meta, use 'm' in place of a language code. Those links will also appear inline.
Note that the 'm' or 'en' or 'zh' or whatever does appear in the text unless you pipe the link.
See also en:Interwiki.