icapd is an ICAP (Internet Calendaring Access Protocol) server, as described in the IETF drafts by Pete O'Leary. It provides calendaring services through the libmcal library's mstore driver.
Open source project that offer summary and download services on this page is a project that carry out their development work on other open source development sites. Their work is linked to this page via a feature called OFI, and their work is not carried out here on OSDN site.