I did find one calendar that has all major christian holidays, church sundays, plus the dates for church leaders until the reformation. It is Lutheran in persuasion, but I am amazed at the detail for early church leader and biblical prophets.
Here is the link I pasted into my iCal Subscribed to: webcal://www.google.com/calendar/ical/LutheranChurchYear@gmail.com/public/basic .ics
I cannot remember where I found it but it has continued to work for a hear and a half. Below is a sample of an entry you get when you double click a name
Justin, Martyr
Born at the beginning of the second century, Justin was raised in a pagan family. He was student of philosophy who converted to the Christian faith and became a teacher in Ephesus and Rome. After refusing to make pagan sacrifices, he was arrested, tried and executed, along with six other believers. The official Roman court proceedings of his trial before Rusticius, a Roman prelate, document his confession of faith. The account of his martyrdom became a source of great encouragement to the early Christian community. Much of what we know of early liturgical practice comes from Justin.
For the basic, no ash wednesday, etc. look at
http://ical.mac.com/ical/Christian32Holidays.ics
Hope this helps