After doing some R&D on a laptop, I got pulse audio working as desired and sent it to HP. Their engineer built from source and compiled it for their thin clients and returned it to us a working build. This build has been moved out to about 20 people and up to this point the only sound they have gotten is standard GNOME login and logout clips.
After testing a few ideas, I have settled on using the mplayer engine, and the gnome-mplayer UI for our deployment. Many of the players have the controls running in a UI separate from the display canvas, which is just not deployable for 'regular users'. Users lose windows in their stack, and often don't know how to find them again. gnome-mplayer is wrapped around the display canvas. It's got only the most basic of controls and should be an excellent fit.
In the beginning of testing, I was concerned that remote display and Compiz would make playback too slow for deployment. However, it turns out that the business use content (quicktime, windows media, real) works just fine. Below I am attaching two shots. The second is the IronMan quicktime (way cool btw!)