http://kcat.strangesoft.net/openal.html is the OpenAL Soft library, which is what you use on almost every platform besides Windows by default anyway. It doesn't expose the hardware-accelerated EAX extensions, but not a lot of people use those. If the Creative Windows SDK doesn't come back online shortly, OpenAL Soft is the only real option remaining.
Not that this is an answer to your question, but... you might consider just using FMOD or Wwise. They are free for hobbyist usage and very reasonably priced for commercial usage, they have a bazillion and one more features than any version of OpenAL, have a much cleaner and less error-prone API, and have designed-oriented tools and support rather than being purely a low-level sound abstraction API.
While I don't know if OpenAL is dead on Creative's site permanently or it's just a hiccup, I really wouldn't be surprised if it was dead. It's very very rarely used in the industry commercially, and is decreasingly used in the indie/hobby scenes from what I've seen. The only platform that really stresses use of OpenAL anymore is Linux. Windows has its own API, iOS and OS X have their own APIs, the consoles have their APIs, and even Android prefers OpenSL over OpenAL. And of course, FMOD/Wwise abstract all those away and give you a single unified high-level API.