Google logged me out of an account and I had trouble logging back in. downdetector also reports Google having issues and friends also had trouble with both.
FWIW for me Google seems relatively stable, but I tried logging into a lesser used gmail account on a lesser used browser, successfully logged in for like 10 seconds, then got logged out.
It's very spooky when supposedly the two companies who probably aren't sharing infrastructure seem to go down at the same time...
