In an interview on Saudi television, the marketing manager for Microsoft's entertainment and devices division for the region revealed Project Natal's launch window: October 2010. GamerTagRadio has the clip of Microsoft's Syed Bilal Tariq saying, "We will be in a position to confirm the date after E3, which is in June. But definitely it is going to be October 2010 and we will have it in Saudi Arabia for sure."
Update: G4 reports that according to Microsoft, "Syed Bilal Tariq is not a [Microsoft] employee ... He is a vendor employed through a third-party company on behalf of the Microsoft subsidiary in Saudi Arabia." The company also wouldn't comment on the alleged October launch window.