As LD says, the new generation of SSDs offer big performance improvements, however they are incredibly pricey per GB of storage, and their production reliability is not yet widely proven. For some specific applications, mostly enterprise, they make sense, but for home desktop systems, even for high end gaming systems, the fastest SATA drives (like the WD Caviar black series) are a much better bet IMO, you get very good performance, and they are cost effective enough that you can have very large storage capacity + redundancy if you wish.
Tom's Hardware has a great write up of the new Intel Sandy Bridge for those interested in specific technical details.