The applications for this are great, and the article touches on a few of them. A laptop could leave the hard drive in sleep mode for longer periods of time, saving battery life, and applications could respond quicker by being cached to the essentially much larger buffer(64mb, 128mb, and above).
True solid state drives have been available for years, but they are way beyond the price range of the typical consumer. A mixed drive probably won't be as big of a hit for the desktop as it will be for the laptop. Imagine, though, having a laptop that can last for 5 hours or more with ease. Hot stuff.