Whats interesting is the Version / Numbering Scheme:-
Beta 4 - Build: 6.1 (10B5126B) - iPhone 5
Beta 5 - Build: 6.1 (10B143) - iPhone 5
Beta 4 - Build: 6.1 (10b5126B) - iPod Touch 5th Generation
Beta 5 - Build: 6.1 (10b141) - iPod Touch 5th Generation
Maybe the dropping of the "B" means non-beta?
Beta 4 - Build: 6.1 (10B5126B) - iPhone 5
Beta 5 - Build: 6.1 (10B143) - iPhone 5
Beta 4 - Build: 6.1 (10b5126B) - iPod Touch 5th Generation
Beta 5 - Build: 6.1 (10b141) - iPod Touch 5th Generation
Maybe the dropping of the "B" means non-beta?