Howdy vediclover,
You can still add new users to WP. If you want them to be able to add events that is certainly still possible, they will just need to be given the editor role on your website or a custom role with add/edit events permissions. To my knowledge this has never changed, though it is possible that behaved differently before I started with the plugin.
If you want other users to be able to add/edit events, like regular subscribers or even unregisteres users, that is what the Community Events plugin is for.
If you want to learn more about user roles, check this out: http://codex.wordpress.org/Roles_and_Capabilities
Please let me know if you have any questions. I am happy to help further, or clarify anything. Cheers!
– Brook