UPDATE: The Mountain Central card (Colorado and Utah) has now been released.
I knew something was up when Garmin named their last topo product with the soon to be dated moniker TOPO U.S. 2008. Now it's official, Garmin will be releasing 1:24,000 scale topo maps of at least the 48 contiguous United States, complete with routable roads and trails. Previously available only for some National Park areas, this software will be known as TOPO U.S. 24K.
These will be available by region -- the Pacific Northwest (WA & OR) is already out, with California / Nevada scheduled to be available in July. The remainder of the U.S. is "coming soon." The maps will come pre-loaded on micro-SD cards with an SD card adapter at $99.99 a pop.