Hi all,
I had mentioned this in the rewrite roadmap, and noticed it came up on IRC as well, so I'd like to run this by the mailing list:
User:The Earwig has written a pure-python (with optional C-speedups) MediaWiki text parser named mwparserfromhell[1]. Currently we have the textlib library and some various regexes that implement this in a non-perfect way. From my experience using mwparser (over 400k successful edits with no issues) I believe it is ready to be bundled with the framework. I think it would still be a good idea to keep textlib in as a fallback or for users who are currently using it and don't need to migrate.
As for actually adding it, in the rewrite branch we can just add it as a dependency in setup.py, and then convert various methods over.
In trunk, I'm guessing we would need to add it as an external. (I'm not sure how that's actually done.)