Wikia offers Semantic MediaWiki hosting
March 12 2008. Wikia – major wiki hosting provider – now supplies Semantic MediaWiki to all of its wiki sites upon request! One of the first wikis that enabled the extension is the Psychology Wiki (though actual adoption has of course hardly started yet). Many more sites on Wikia suggest interesting and promissing uses of SMW, and support from experienced SMW users is of course appreciated to ease the fruitful introduction of SMW on many such sites.
Here are some more links where you can find further information (and participate in discussions if you like):