This morning http://buyarug.co.uk, a Magento site that we operate, was showing a white screen of death. Checking the apache error log revealed the following error:
PHP Fatal error: Call to a member function getDir() on a non-object in /DOCUMENT_ROOT/app/Mage.php on line 328
After some investigation the problem proved to be intermittent and caused a white screen when requesting a page, yet hitting refresh the page would load, then it would break again and so on.
We've just finished testing our new custom module for Magento that allows developers to do A/B or multiple variant testing of all the pages within a site - it'll be going live for one of clients tonight. With Magento growing in popularity as a way to deliver high end e-commerce solutions A/B testing is going from being a nice to have to an essential for those serious about site development.