The old unix reminder system, "remind", is what I use as the core of my calendar system. It's very good at parsing dates in different formats and is based on text files with lines such as "REM <date string> MSG <text relevant to event>".

The reason I like it is the fact systems such as your idea there could possibly be built on top of it. Say you parsed out any portion you saw as a date string and put that at the front, it might be smart enough to handle several date string formats.