TL;DR: Microsoft and OpenAI announced a new version of Bing featuring "a new, next-generation OpenAI large language model [..] more powerful than ChatGPT", and that Microsoft Edge will feature a Copilot-like assistant that helps with composing and summarizing content. 

Brief thoughts/comments/notes:

• Microsoft's attitude during their press meeting seemed pretty aggressive and targeted directly at racing with Google. This seems kind of bad. For example, a quote from Nadella:
  • "The race starts today, and we’re going to move and move fast. Most importantly, we want to have a lot of fun innovating again in search, because it’s high time."
• Microsoft built a scaffold for the new LM called "Prometheus", that lets them "best leverage its power". 
• Microsoft has also used the new LM in their Bing search engine, though it's not clear exactly how.
• This seems way more hype than Google's Bard announcement.
• You can register for the new Bing beta on the Bing.com site.