I just obtained the iPhone beta 8 firmware and have extracted the contents. I tried running this firmware through gzDecryptor (yes I am on windows :p), but it could not decrypt the ramdisk or find the rootFS decryption key. I also tried manually decrypting using an img3 unpacker, which has worked on previous betas, but no luck. It looks like Apple has put extra encryption in this beta firmware version. Anyway, if anyone has had any luck decrypting the ramdisk or rootFS please let me know how, either by reply or a PM.