iOS 5 Beta 1 Expiry Date Is August 4 2011

The expiration dates for iOS 5 beta 1 is August 4, 2011.

Apple's first beta of the next generation iOS firmware, iOS 5 beta 1 will finally expire on August 4, 2011.

Source:
http://www.chiphazard.com/2011/06/16/ios-5-beta-1-expiry-date-is-august-4-2011/