Comments and suggestions regarding implementation of Calendar integration for Confluence....
A calendar might be implemented as a filter through which other content would be re-organized in the temporal domain. News items are already visible through a calendar filter, but, all content has creation and modification dates. Perhaps the new label capability could be exploited... labels could be applied to content items that would tag those items as attached to a particular date or date range, perhaps even date and times, etc.
Guy Fraser comments "...having recently been involved in several discussions with David Peterson and various members of Atlassian and the developer community, I'm now convinced that labels are not the best way to implement such features. Perhaps some form of "page category" or "page type" attribute could be provided to fulfil our desires - this would leave lables to their designated role (categorisation of content, regardless of the type of content) while the page category/type would be used to link in the temporal elements?"
Guy's susggestion sounds reasonable to me (Larry Talley). It appears that the concept of page category/type exists already, as the advanced search feature presents the following as "types" of content: Pages, News items, Mail, Comments, Attachments, Profiles, Space Descriptions.
Another idea that might be considered is to integrate with an independent calendaring product, with minimal adaptations to Confluence. Perhaps there is a terrific Calendar product out there that has great features for temporally-organized content, but little or no capability for other organizations. The Open Source Applications Foundation Scooby project discusses some interesting Calendar systems.