This post is a bit late - the firmware version 1.2 was published already in July this year: http://panasonic.jp/support/global/cs/dsc/download/fts/index2.html. I have updated the body at the first days when it came out, but first come to try to actually upload some files over wifi only now. It worked, but not from the first time - I had to google a little bit for how I do it. I came to success by following the instructions at http://www.lumixgexperience.panasonic.co.uk/forum/viewtopic.php?f=40&t=3931, but later also found a step-by-step with screenshots here: http://www.personal-view.com/talks/discussion/5389/gh3-wi-fi-questions-and-apps-discussions/p3 (scroll down to post by @maxr). The only thing he has forgotten to mention is that you may need to also change firewall settings to enable file sharing. Firewall settings are available under System Settings -> Security and Privacy -> Firewall. Press "Firewall options..." and unset the "Block all incoming connections" checkbox if it is set.
From my side I want to stress that you need to change in the "Settings for transferring images" image quality to RAW+JPEG: when you see it for the first time be quick to press the display button, it disappears very fast. And if you missed that, the default setting is JPEG only - you will not be able to transmit any RAW files.
The overall process is very slow - it takes several minutes to set up a connection, but if you need it - it works.