After getting a tip regarding a possible delay on the 2009 Zero S electric motorcycle, we contacted the company for confirmation. It seems that the original motor used in the S model was prone to overheat under certain circumstances in testing. A new motor is now being used that reportedly fixes the overheating problem and also allows for a slightly higher top speed.
As it turns out, the company has already shipped a small number of 2009 models to customers, and those with deposits already in are being contacted and offered their bikes right now with certain unspecified limitations or a free upgrade to the 2010 bike with the improved motor and a number of other unknown enhancements. It's not entirely clear when the new 2010 model will begin shipping, but our tipster says the company is looking at April. Thanks for the tip, Nic!