Heroku's provisioning, build, and remote console services have been down for a few hours. Luckily my production app is still chugging along pretty well. There was a time this afternoon when I wanted to restart one of my six dynos (because it was half-dead) but was unable to due to the API lockdown. That meant every sixth request was sent to an app server that was likely to barf on it for a while there. The dyno got better a few minutes later though.
Postmortem edit:
API outage is over after a period of about three hours (that I was aware of anyway). During this window my app's response time was about 1500ms. Now that it's over it's down to about 250ms, which is on the high side of our daily variance between 150 and 250.
Unfortunately for us, we pushed out a marketing newsletter right about the time they shut down the API. Looks like we're still getting decent sales though!