Speaking as a jailbreaker, this is actually incorrect. At least as of previous revisions, the UID key lives in hardware - you can ask the hardware AES engine to encrypt or decrypt using the key, but not what it is. Thus far, neither any device's UID key or (what would be useful to jailbreakers) the shared GID key has been publicly extracted; what gets extracted are secondary keys derived from the UID and GID keys, but as the whitepaper says, the passcode lock key derivation is designed so that you actually have to run a decryption with the UID to try a given passcode. Although I haven't looked into the newer devices, most likely this remains true, since there would be no reason to decrease security by handing the keys to software (even running on a supposedly secure coprocessor).
But it is an absolute certainty that communications technologies built and operated by major American industry are wholly compromised. To believe otherwise is to grossly misunderestimate the nature of State intelligence actors. The historical record is clear that big telecom + hardware providers have always been in bed with State power, both in America and elsewhere, and the Snowden docs pretty clearly show that's still true today.
Maybe Apple's announcement means that the county sheriff can't read your teenage son's weed-dealing text messages. But if bin Laden had an iPhone, the men in the windowless buildings would beyond a shadow of a doubt be reading his communications, probably via seven or eight independent attack vectors (not counting the compromised publicly switched telephone network, over-the-air signals, etc.)
If you have secrets, keep them off of communication technologies run by large companies. Especially when those technologies are 100% closed source and the companies in question have openly admitted including backdoors in previous versions of the tech you're currently using.
Also look at the sworn affidavit that EFF obtained from local SF bay area whistleblower Mark Klein -- an AT&T technician who revealed the existence of the NSA's fiber taps at the 2nd & Folsom Street SF facility.
There is no such entity as "major American industry." There are different companies with different incentives and different willingnesses to protect their users. Some companies do the right thing; others don't.