This PR announcement isn't the only data point, GM has the goods to back it up.
Looks to me that they designed a mass-producible car outfitted with self-driving systems (which is very cool!). But they are only just starting to do employee testing. Waymo has been doing that for years.
Waymo has since been proceeding a bit more cautiously, and their efforts at this point are oriented more towards smoothing out ride feel, testing under adverse weather conditions, and their early rider program in Phoenix.
Whether it's Waymo or GM to officially be the first to have an empty car driving on public roads, the other won't be far behind, though the victory will be largely symbolic. GM's cars still need a lot of polish, and Waymo needs better manufacturing partnerships.