The GetNetworkUsers operation has always had an optional 'perm'
parameter which lets you specify the types of users you want to get
(user/guest/admin). Prior to today, if you included an empty 'perm'
parameter, everyone would be returned. After today's deploy, an empty
'perm' parameter means that no one will be returned. If you omit the
parameter entirely, we will continue returning everyone.
Documentation:
http://secure.pbworks.com/api_v2/?q=GetNetworkUsers