No. The *rendered article* is cached, and shared
between all the users
(which can't be done if a piece of it changes between users), as opposed
to the bar where you see your name.
You can disable caching on your preferences, though.
I think a few versions are cached, depending on prefs (date formats,
stub links, etc). Each version is only shared between those with the
same prefs. Of course, this results in far fewer versions that giving
each user a different version. (I stress the "I think", I've never
fully understood the intricacies of MediaWiki's caching.)