The roadmap for the Open XML SDK was unveiled yesterday, which plots the path of the SDK all the way into the Office 14 timeframe.

The original CTP version of the SDK was released in June 2007.The updated CTP is expected next month (April 2008), with a v1.0 release set for May 2008.

timeline

Go here to find out what's coming in the v1.0 and v2.0 releases.