GPT-4 is out. There's also a LessWrong post on this with some a lot of discussion. The developers are doing a live-stream ~now (yesterday).
And it's been confirmed that Bing runs on GPT-4.
Also:
Here's an image from the OpenAI blog post about GPT-4:
(This is a short post.)
I think it's referring to the version of GPT-4 with RLHF, which I believe Bing/Sydney doesn't have? Bing/Sydney being based on the pre-trained version or the fine-tuned version, most likely.