Interfacing external applications and utilities with wiki systems
I recently came across Prosper (http://prosper.sourceforge.net/) - which is a latex class for producing presentations from latex source. I am quite pleased with features - it gives control over animation and almost all aspects. Another application that I came across was jfree (http://www.jfree.org/jfreereport/index.html) a suite of java libraries that allow you to produce nice tables and outputs using XML definitions.
And the typical requirement is to collaboratively edit the sources and to generate the final files using these applications. There are two key problems: The input is in their native format (jfree may use XML) - and it is better to use wiki markup. Second, there should be a nice way to interface with external application so that the responsibility of writing connectors lies with these package owners and their users, rather than wiki system authors.
I think a unified mechanism for achieving these - across all wiki systems - is what we require here. More we standardize on wiki interfaces, more benefits will follow. Unfortunately, there is no standardization effort for many aspects of wiki systems - and that is indeed a bad news.