This joint announcement with California governor Newsom and Elon didn't have much direct information filling the ~10 min they were on stage talking, but it was clear signaling that Newsom and Musk are still on good terms, or at least they both want to project that image in public.
The governor was speaking very positively of Tesla and Elon, holding the company's leadership up as a monumental example of California's success in fostering manufacturing, innovation and EV technology. Gavin Newsom is also probably the most well-known and influential state governor in the Democratic Party nationwide, so this is pretty significant in my opinion. Elon and Tesla are being praised instead of shunned and ignored, with Newsom saying stuff like "It's a point of pride--always has been for me--that Tesla is a California company. It started here first." and bringing up that he's known Elon for two decades and was one of the first Roadster customers in the early years.
Note that Newsom's most well-known and influential Republican counterpart is governor Greg Abbott of Texas, who has also recently had similar kind words for Tesla and Elon, except more oriented towards hyping up Texas of course. For example:
In the last three years there has been an apparently rocky relationship between government in CA and Tesla, and this is a positive sign in my opinion. Tesla does not always have political leaders on stage with Elon at reveal events, like the Cyber Rodeo for example.
When Tesla relocated the global headquarters to Austin, Elon insisted that Tesla would still continue to expand and hire in CA. Today we got more concrete information on what some of that expansion will look like, so it's not just empty promises. I think this event today should help assuage concerns that Elon has managed to alienate Tesla and the D Party politicians and that this would materially harm the business in terms of governmental resistance. Based on the actions of both Abbott and Newsom it would appear that both sides are being played well enough. By the way, 21% of the US population lives in either CA or TX, so these two governors are politically representing more than 1 out of 5 Americans.
This announcement also indicates that Tesla will not be reliant on recruiting top AI and software talent to leave Silicon Valley for Austin, which there has been some concern about. Tesla is developing teams in Palo Alto and Austin.