Some notes on Confluence 2.8...
Confluence 2.8 has been released and now has much better separation of content and design, making it easier than ever to customise pages within Confluence using Theme Builder's "Custom CSS" options.
Theme Builder 3.0.2 (current stable release) will not work with Confluence 2.8 due to some API changes within Confluence, however Theme Builder 3.0.3 should be out fairly soon.
Any customers who have upgraded their production environments to Confluence 2.8 before testing in a staging environment should contact Adaptavist Support to get a snapshot release of Theme Builder 3.0.3 which will get you up and running, albeit with ugly breadcrumbs.
Adaptavist strongly recommend that customers try all upgrades of Confluence and any plugins in a staging environment before rolling out to a production environment. We've seen a steady increase in the number of customers upgrading the production instances of their mission-critical wikis without doing any testing beforehand - it's not a good way to upgrade your wiki!
Atlassian now provide free Developer or Test licenses for staging environments and Theme Builder will automatically run in "Free Mode" on such installations to encourage customers to test upgrades before releasing them to end-users 
It should be noted that we've had a growing number of reports that Confluence 2.8.0 is using quite a bit more RAM and server resources than earlier versions. Our initial tests of the final release are also showing similar issues and we will continue to investigate and provide feedback to Atlassian.
We would advise customers who are not desperate to upgrade to Confluence 2.8.0 to wait for Confluence 2.8.1 before upgrading – let the early adopters find any new bugs and wait for the 2.8.1 bug fix release (always good practice in mission-critical environments).
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It should be pointed out that Builder 3.1.3 is now released and available Here