Just go to: http://esupport.sony.com And select downloads/drivers and get to your camera model. I know for the NEX-6 it's mainly to allow support for more lenses for hybrid AF.
Updating now! [box] NEX-6 Camera Firmware Update What Does This Do? This utility updates the NEX-6 camera firmware to version 1.01 and provides support for the following Fast Hybrid AF compliant lenses: SEL1018, SEL35F18, SELP18200, SEL30M35, SEL50F18, SEL18200LE Note: When using the SEL30M35, SEL50F18, and SEL18200LE lenses, please update the lens firmware to the latest available version. [/box]
If you have one of the lenses that needs an update. Example, the new 10-18 was designed for hybrid AF out of the box so no FW update needed.
I updated the 18-200 the last time the FW was issued for the lens so it looks like I am good for now. ; Do you have a link to the lens FW pages?
I believe the update may cover the 18-200mm original - so if you haven't already, you should make sure that lens is attached and receives the latest firmware update to make sure the PDAF focusing works with that lens.