If somebody is interested, I wrote an extension for embedding (the upcoming) Google waves in MediaWiki as a tag extension:
http://www.mediawiki.org/wiki/Extension:GoogleWave
If someone has a wave developer sandbox account I'd be glad if that person would help me test the extension a bit more than I'm able to do by my self. A preview of the extension is avalible at http://mickenordin.se/wiki/Wave for now (I know, my wiki looks more like WordPress than MediaWiki :)).
If nothing shows up try this: http://mickenordin.se/mediawiki/index.php?title=Wave&action=purge
/Micke