Tomorrow (September 1) is the beginning of the Church year on the Orthodox calendar. My own Church, the Orthodox Church in America, follows a revised Julian calendar which tracks the civil calendar for most dates, but calculates the timing of Pascha (Easter) according to the traditional reckoning. (For those Orthodox Churches that use the traditional Julian calendar, September 1 is still thirteen days away. Orthodoxy being conservative in all things, many Churches have declined to use the revised, or "New" Calendar and, in some circles, the change is viewed as the first step of a descent into secularism and relativism.)
The custom of starting the Church year at the beginning of September dates back to the times when Orthodoxy was the official faith of the Eastern Roman Empire. Even in these more secular times, it is still the custom of Orthodox hierarchs to send a word of greeting and encouragement to their flocks at the beginning of the new Church year. The message of Metropolitan Herman, new chief hierarch of the OCA can be found here. Archbishop Demetrios, head of the Greek Archdiocese, sends his greetings here.