Edit summaries (referred to as comments internally, see Linker::formatComment) have their own custom parser, which is possible to duplicate but rather annoying to get 100% correct (also, there are minute differences between versions of Mediawiki).
It would be nice to be able to parse edit summaries via the API in two methods:
- add comment= parameter to action=parse, spitting out <parsedcomment> with the HTML
- add &parsecomment to all properties returning unparsed comments, for example http://en.wikipedia.org/w/api.php?action=query&prop=revisions&titles=Foobar could have &parsecomment return: <rev ... comment="/* Examples */ capitalization" parsedcomment="(<span class="autocomment"><a href="/wiki/Foobar#Examples" title="Foobar">?</a>Examples:&#32;</span> capitalization)" />
Not sure of the exact names, but internally and in the api they are called 'comments' rather than 'summaries'. In Linker the action is 'format' but api users will be used to 'parse' already.