You can read about it here: http://panasonic.jp/support/global/cs/dsc/download/fts/index2.html
As I see it, it's all about 3D-performance.
But I recall that the upgrade is important if you wish to update any lens as well. That what they told me when I updated my Sigma 30 2,8
|Fangorn Forest by cand1d|
|Yosemite Falls with Moonbow by Jonathan Shapiro|
from Best Landscape of the Week 4