Thank you for your patience with this plugin. We are currently looking Calendaring in Confluence and have been researching possible solutions for improving the Calendaring experience in the product.
If you are interested in participating in some customer feedback, surveys or early access to some prototypes for Calendering please email me (smansour at atlassian dot com) so I can add you to our feedback list. Alternatively, continue to watch this issue and we will update it as we make further progress.
The existing calendar plugin is known to work in Confluence 3.3/3.4, even though it isn't formally supported. As always, we recommend you test the plugin before using it in a production environment.
Confluence Product Manager