At my app agency Agant, we created a handy checklist of all the things you should test before releasing a new app (or app update) to the App Store. I thought this might be a useful thing to share with other developers. Here it is, as a Pages document and a PDF.
This document is by no means comprehensive, and is not a substitute for more thorough testing (including unit testing) of your code. Nor is it a replacement for usability testing of your interface and app flow. It is, however, a useful way to remember all of the things that can easily catch you out. Testing your app with a 24-hour clock, or in a different timezone to your own, can find easy-to-fix problems before they hit the Store. And getting someone else to use your app with Screen Curtain is a great way to test whether your VoiceOver support is truly useable in practice.
Please feel free to use and adapt this document as you see fit for your own testing, and do post any additional testing tips in the comments, or send them to @daveaddey on Twitter.
Update: 22 September 2013
Oisin Hurley has set up a GitHub repository for the App Release Checklist. Please do add your own checklist items and suggestions to the list on GitHub, and / or use it to create a branch of the list for your own needs.