Apple just released iOS 8.4 beta 3 for developers under the build number 12H4098c. iOS 8.4 beta 3 is available for iPhone iPad and iPod which is capable for run iOS 8. You should have registered for iOS developer program to download iOS 8.4 beta 3. Alternatively anyone can download iOS 8.4 beta 3 on third party websites as IPSW files.
Jailbreak iOS 8.4 beta 3
i0n1c has triggered the iOS 8.4 beta 3 jailbreak competition with his tweet. Indirectly he has clued that he can easily jailbreak iOS 8.4 beta 3. But we do not hope i0n1c will release a public jailbreak for iOS 8.4 when we considering his previous behavior. Check the i0n1c’s tweet about iOS 8.4 beta 3 jailbreak below.
I cannot jailbreak iOS 8.4 beta 3 because I have no internet capable of downloading it at the moment.
— Stefan Esser (@i0n1c) May 11, 2015