We've recently pushed out some nice changes to our logging facilities. This includes a new log viewer which allows you to watch activity live in your browser in an easy to use interface.
Logs are also easier than ever to find - just go to your Application menu and then select Logs and this UI will pop up for you. Down the left of the window are all the available log options for your current deployment.
We log all output sent to STDOUT and STDERR from any of your running processes. We store the last 2,000 lines from each process.
Full details about logging functions can be found in our docs