Wikipedia:Mailing lists
Wikipedia has a number of important mailing lists for general users and administrators. Mailing lists are available in a number of formats: via a web archive, by email, or by NNTP using the mail-to-news gateway GMANE. Mailing list posts are indexed by search engines such as Google.
The general project-wide list is Wikipedia-L. It's a resource for Wikipedia authors. If you don't want to use Wikipedia (or Wikipedia:meta-Wikipedia) for questions, or if you'd like to talk to other Wikipedians outside the wiki format, then you can sign up for Wikipedia-L.
Since Wikipedia-L developed into an extremely high traffic list, a separate mailing list for the English Wikipedia was created. For discussion of issues concerning the english wikipedia only, please sign up for WikiEN-L and keep Wikipedia-L for general policy discussions!
There is also a general mailing list for interlanguage issue discussions and cooperation: Intlwiki-L. Use this list for things that specifically concern cross-language issues, or for discussing the setting up of a new language.
There are also language-specific mailing lists for Wikipedia in Danish, Dutch, Esperanto, French, German, Japanese, Polish, Portuguese, and Swedish.
And, there's a mailing list for technical discussions regarding development of the Wikipedia software: Wikitech-L.
New textbook development page for the soon-to-appear Wiki Textbook subdomain.
Wikipedia also has a real-time chat channel. Visit Wikipedia IRC channel for more info.