Selknam
It's working in the RC version! Likely some user interface tweaks still required, but just as a teaser:
You can manage containers, create more, etc.
You can define certain domains/ websites to auto open in a specific container.
Right-clicking on a tab lets you request the site be reopened in a particular container
And if the site is already in a container, you can have the option to reopen it not in a container
