The first bit that comes along is a slew of new connectors, four to be exact. They are a slimline connector for SATA optical drives and an internal micro connector for 1.8 inch HDs. Both are just physical compactions of the standard SATA connector you all know and love.
Slightly more interesting is an external and internal multilane connector. These are there to support the second bullet point, multi-lane SATA. This combines four lanes into a single connector for external RAID boxes and things that need multiple devices or huge bandwidth. Four for the price of one eSATA port.
The next two are interrelated, both NCQ additions. The first is NCQ priority, and it does just what it says. It allows certain streams to be prioritized. It doesn't take a genius to figure out why this is a good thing. Video multitasked with anything else can be problematic without this as bit rates climb.
The last one is a bit more esoteric, it is called NCQ unload. This spec is aimed at laptops, specifically falling ones. When modern laptops sense they are falling, they tend to park the HD heads to save the drive. In my opinion, this is one of the most useful laptop features since the LCD.