A item which has driven me a little nuts since our original implementation of CSX (SBS), has been a lack of layout flexibility (horz. vs. vertical) for the user bar and it's assets. On site's such as Jivespace (not seamless UI integration with the Jive Software site), the horizonal layout of this userbar works well as it provide the primary navigation and utilities. However, in implementations where sbs is being more tightly integrated with a parent site, the parent might already provide primary nav and utilities which must carry throughout. In turn this would turn SBS nav into a secondary or tersiary (contextual to where you are at) navigation. From a layout perspective, it's a little less desirable to stack multiple horizontial bars on top of each other, as this creates noise and loses it's hierarchical structure needed for the overall site experience.
It would be nice to have a layout option which allows the user bar (minus search as it could be pulled out as it's own container) to be oriented horizontially or vertically. A feature that jumps out at me in sbs is the "Other Places" accordian. You could possiblly modify the current actions panel to house new (actions), your stuff, history, and browse.
I'm interested if any other company's have run into this same challege, and if so, what solutions were taken up.