It's my great pleasure to announce the release of a new MediaWiki extension, Semantic Calendar. This extension uses a parser function to turn any page into a monthly calendar, displaying pages that contain semantic date information. It also allows for querying, in the manner of the #ask function, to filter the set of results displayed. Its reliance on SMW makes it, I think, the easiest-to-use of all the calendar extensions: there's no need for special categories or naming of pages. The single complication of this extension is that it requires that caching be turned off in the wiki that uses it, to enable correct display and querying of the data (there might be a way around this requirement eventually).
You can see the extension page here:
The development of this extension was funded by IdeaCrew for use on the FEMA Region III Levees Wiki; you can see the calendar in use here:
Feel free to download it and try it out; for now you can send any bug reports, suggestions etc. directly to me.