The adaptor/sync mechanism works both ways:
http://tiddlywiki.org/wiki/Synchronization
There should be a list of tiddlers originating from your MediaWiki
instance (that's assuming you've selected "Keep these tiddlers linked to
this server" when importing), which allows you to push changes to the
server (provided the respective MediaWiki instances is configured to
accept edits via the API).
You might be interested in MediaWiki Unplugged:
http://mediawikiunplugged.com
-- F.