Add calendar event with an Activator action. An uninteresting tweak with somewhat interesting technicality since Activator actions must live in SpringBoard but also it needs to talk to the calendar app and hook that. for a compiled form of this Activator action add http://orikad.com/repo to Cydia. To compile this use Theos http://iphonedevwiki.net/index.php/Theos/Getting_Started