Not quite yet - when the first preview builds are available, they'll be in the Microsoft Store.

Also stay tuned for Rajesh Jha's keynote later today, with our official announcement. It'll have some other relevant information I don't think any of the articles have mentioned quite yet :P

Can you link the session, please?

I believe this https://mybuild.techcommunity.microsoft.com/home#top-anchor is the link, but I honestly don't know.

It's live now, and I think Windows is up soon, though I don't know where in the keynote we are.