If it is any consolation, mine was built on 5/17/10 and had an ETA of 5/29. My dealer checked the status on 5/26 and the ETA was gone. Best estimate then was mid July. Last week my dealer informed me that it was in transit (confirmed by Ford) and should be here by 6/30 but Ford still doesn't show an ETA. Yesterday, they said it was on a truck and should be here any time. I also got this email from Ford Customer Care yesterday,
"Thank you for your patience as we launch the best Mustang ever. As with all new product launches, we make every effort to ensure the highest quality of our vehicles. With summer sales ramping up, there have been questions regarding the status of 2011 model year Ford Mustang orders, particularly retail units. As of today, Ford is currently building and shipping all 2011 Mustangs - V6, GT and GT500. In addition, all currently built retail customer orders have been prioritized (oldest to newest) for shipping from the assembly plant by the end of June.I sincerely apologize for the delay and we promise it will be worth the wait."
Mine still doesn't have an official ETA but is on its way. Yours may be too.