We now have a public and cached Parsoid API available at
http://parsoid-lb.eqiad.wikimedia.org/
It implements this interface:
https://www.mediawiki.org/wiki/Parsoid#The_Parsoid_web_API
http://www.mediawiki.org/wiki/Parsoid/MediaWiki_DOM_spec
GET requests are normally expected to pass the oldid parameter:
http://parsoid-lb.eqiad.wikimedia.org/enwiki/Main_Page?oldid=574690625
Current revisions of pages will very likely be in cache (they are
pre-parsed after each edit), so you can retrieve those without causing
extra load on the Parsoid cluster.
This API is expected to be followed by a full content API by early next
year. This API will expose the same functionality and HTML+RDFa, so
consumers will only need small changes to switch to the new content API
then.
Gabriel