When using authentication, the username is recorded when the page is edited and is diplayed in the version list among other places.

First setup the Authentication module.
!|Authenticator Setup|
|username|password|status?|
|Aladdin|open sesame||

Create a page to be requested.
!|Page creator.|
|Page name.|valid?|
|FrontPage |true|

No save the page a couple times wih the user logged in.  This will produce a version edited by the user.
!|Response Requester.|
|uri|username|password|status?|
|FrontPage?responder=saveData&pageContent=hi+there&editTime=0&ticketId=0|Aladdin|open sesame|303|
|FrontPage?responder=saveData&pageContent=by now&editTime=0&ticketId=0|Aladdin|open sesame|303|

Now load up the version list.
!|Response Requester.|
|uri|username|password|status?|
|FrontPage?versions|Aladdin|open sesame|200|

The user name will be in a <TD> element without any extra characters.
|Response Examiner.|
|type  |pattern|matches?|contents?|
|contents|>Aladdin<|true||