Following the release of Magento Community Edition 220.127.116.11 last week Magento also silently updated it's Magento User Guide for the new version. With 296 pages it's only 5 pages bigger than the 1.7 User Guide but since most changes are "under the hood" and not something to add to the user guide that was to be expected. Good to see Magento releasing the updated User Guides right along the release of the software itself! You can download the 1.8 guide at magento.com.
Recently I've seen some (often absolute) statements going around, generally in the line of "open source commerce platforms are a terrible idea". Now of course different solutions always have different pros and cons.
A hierarchy of evidence (or levels of evidence) is a heuristic used to rank the relative strength of results obtained from scientific research. I've created a version of this chart/pyramid applied to CRO which you can see below. It contains the options we have as optimizers and tools and methods we often use to gather data.