Apollo supports iCal feeds!
Interaction between programs is crucial — especially in the Internet era, where lonely desktop programs are the dinosaurs, and online services can all communicate. An area where communication is especially important is calendars: people want to be able to check their appointments on their phones, and add them on their PCs for example. iCal is a great standard to synchronise different calendars in different locations. This is why Apollo now fully supports iCal.