Does anyone know if Heroku is still with Facebook?
The formal Facebook integration is no longer available.
However, independent of whether or not the button to create a Heroku app is on Facebook or not, you can always create an app on Heroku that integrates with Facebook. You'll just have to manually perform the administrative and configuration steps that were previously automated.
You mentioned wanting the default Python app? You can find the various Heroku/Facebook app templates in GitHub: