Just a word of advice: Today I revamped our HTML structure, our columns functionality, added several new widget areas (while renaming the old ones), and a lot more. All of these changes are currently in the subversion repository, feel free to check them out, however understand that if you already have a site up and running, these changes are not likely to play well with any widget setups, styles or child themes. It is as usual best to stick with actual release for live sites.
There will be more on this soon, but consider this both a warning and a heads up, if you want to adapt your child theme or style for the next major release of K2. These changes, which massively simplify K2 and were previously planned for v1.2, but will instead find their way into v1.1, are meant to make K2 easier to get around.
The short-term downside is that there will be some extra work adjusting existing styles and child themes; but it’s definitely worth it (and should have been done a long time ago).