“Branding” WebCenter Spaces in PS3 is easy! There is support for complete management of “Site Resources” (like Page Templates, Navigations, Skins, etc.). Powerful browser-based tooling allows business users to easily create, edit, and manage these resources. Part III of User’s Guide covers these topics in detail.
A great post (and video) by John Brunswick here shows an example on how one can quickly create a new Page Template with “flyout-menus” using CSS.
Here are some screen shots of a Page Template we built using similar techniques.
Flyout menus include links and content (images) defined in the Navigation Model
Flyout menu surfacing Administration links for the space