Google using invalid security certificate

It appears that Google is using an invalid security certificate across many of its domains.  If you type https://gmail.

It appears that Google is using an invalid security certificate across many of its domains.  If you type https://gmail.com or https://google.com/adsense into your favorite Web browser, here's what you see:

Very strange.

After last year's warnings around sidejacking, I made it a habit to use "https:" connections for GMail only to run into this secure connection failure.