How can I recover from failed app update?
This has now happened a couple of more times. I've been able to resolve this the last couple of times by tapping the app back on the main screen (ie not in the app store). The label below it changes to 'Waiting'. Then tapping it again it changes the label to 'Loading' or 'Installing' and the update finally completes. I can then update other apps.

Otherwise the only other solution is to delete and reinstall the app.