Karsten - excellent suggestions.

I'd like to add my voice to this topic. I suggest that Mediawiki.org needs to install SMW so that extensions' installations can be programmatic.  I am working on upgrading SMW+ extensions to MW LTS, one of which is the Wiki Administration Tool.  Redesigning that extension to be more palatable to the SMW community has convinced me that mw.org needs to have publicly accessible data about each extension, most importantly dependencies. 

- john