Yesterday, I viewed a webinar held by Sogeti on End to End Testing with TMap (their registered test methodology).
I am not familiar with TMap and I'm about to educate myself on it. But that's for tomorrow.
In the meantime, without any knowledge of TMap, the webinar itself is very informative on the subject of End to End testing and covers a systematic way to execute such testing.
The Webinar defines E2E testing as typically a wider test and a test project in itself, covering multiple integration systems.
The Webinar is available at: http://www.sogeti.ie/en/News--Events/Events/e2e-testing/
My notes are available at: http://www.test-soft.com/cms/index.php?option=com_content&view=article&id=77&Itemid=96