According to code digging developers, 9to5Mac notes yesterday’s newly released iOS 5 Beta 5 will be released next week on Wednesday, August 17th at 5PM PDT.
@iH8sn0w claims a September 14th expiry date for iOS Beta 5:
How many betas will Apple release, before seeding Golden Master to developers? TiPB points out the history of iPhone OS and iOS betas:
iOS 2: previewed March 6, 2008, 8 betas, released July 11, 2008
iOS 3: previewed, March 17, 2009, 5 betas, released June 17, 2009
iOS 4: previewed, April 8, 2010, 4 betas, released June 21, 2010
iOS 5: previewed June 6, 5 betas to date, released ?
Golden Master seeds will given to developers before they become mainstream, and given that iOS 5 is set to launch this Fall (oh, and possibly the iPhone 5 too), the GM seed appears to be imminent.
