What is this Dash? Is it only on the SVN, as WAU isn't picking it up. I'd like to give it a try
I assume they are talking about http://www.wowinterface.com/downloads/info7391-Dash.html. I haven't given it a shot yet but I remember someone on the EJ forums posting about making a "Dock" style addon where you could park things that you dont use often but still want to have semi-visible or easily accessible. It had nifty mouse-over animation popouts and everything. Dash sounds like the same sort of idea, you park stuff you don't want to see often on the layer and then use a keybind to toggle viewing those frames. Addons like this will help clean up a lot of clutter.
Something similar is Tooggle. File is on wowinterface. It has a hotspot feature as well as ability to toggle sets of add-ons and swap them. I usually use this to swap things like omen (in combat) and assessment (out of combat), hide SL Timex and chat frames as well as hiding a utility Bartender3 bar with things like hearthing.
I use the lua scripting in ee panels to auto hide things like the utility bar when entering combat, and to auto switch to omen on combat and switch back out to asessment when leaving combat.