I've had a few customers trying to understand the format of the Exchange Activesync logs and how they are constructed. 

I found out there are two great articles available covering the formats of both Exchange 2003 and Exchange 2007.

Exchange 2003 SP2 http://msexchangeteam.com/archive/2005/03/28/403047.aspx

E12 http://www.exchangeninjas.com/ExchangeActiveSyncProtocolLogging