The SSD is certainly superior technology to the HDD in many respects. The SSD has more speed, needs less power, and can last longer since there are no moving parts to wear out. The downside to the SSD is that the things are expensive.
That last caveat means that the SSD is more common in the enterprise market than the consumer market. Maxwell Technologies has announced that its BOOSTCAP Ultracapacitors are now being integrated inside SSDs for the enterprise environment.
The capacitors offer 10 to 25 farads allowing the SSD to have an internal battery backup. The power stored in the capacitors allows write operations to complete in the event of a power loss. The capacitors are also small enough that the SSD form factor doesn't have to be changed.