I gave a presentation at HTML 5 dev conf on the topic of using HTML 5 on top of an existing API/business architecture. During the QA session and then offline, many people asked me about real-time app monitoring.
As we are getting close to launching our application I wrote a blog about our strategy: http://goo.gl/d9Zur . Thought I would share as it could help you in your live bug hunting adventures.
Do note that this is just one approach amongst many, not a popularity contest :)
Hope this helps, let me know if you have any questions or comments.