Update:

> it's now actually announced to be another CPU called S1 by a
> chip design company called Solid Silicon

Solid Silicon has joined the OpenPOWER Foundation as platinum member:
https://openpowerfoundation.org/members/solidsilicon/

...and it has raised 100,000 USD in a funding round in February:
https://www.crunchbase.com/organization/solid-silicon/company_overview/overview_timeline