Trying to figure out where you can find All Users group in SharePoint 2010? Microsoft has added lot of new helpful features to SP2010 but removed some of the features from SP2007. But don’t worry, there is a work around in getting to what you need.Here are the steps in getting all the Users in the current site.
Site Actions => Site Settings => People and Groups (User and Permissions Section)
Now you will be at the default group for that site. Go to the Browser location and replace the query string after people.aspx with the below query string