Lumix GH2 is indeed fast in focusing be it at 14mm or 300mm. I can't say anything about UWA lens as I didn't have one at hand.
Here's an image of the GH2 in action with a 100-300mm shot using handheld at 300mm. Sorry I cannot include the picture of the semi-naked man walking around as it might add unnecessary issues for me. For I think it might be a good example of a sports shot as its also done handheld. Please use your imagination for that part.
Good thing about the 100-300mm lens is that it feels like the 45-200mm in weight. But I personally feel its still a long way to using it for bird watching... Need the upcoming 800mm, please come before I grow fungus.
Video tethering is still under rumor so I won't add any additional fuel to it.
If you think this is just a video camera then you are dead wrong. Mix this with a fast prime lens, 20mm or my upcoming fave 14mm F2.5 and you have a fast camera that you can shoot while running. Good for those with criminal intentions, but please don't quote me.
Only three things I don't like,
1) It still don't detect well in the dark, usable ISO is 1600 (double of GH1) and if you close two eyes and photoshop then maybe ISO 2000 - 3000.
2) Battery size caught me by surprise, its a high capacity smaller battery (half as thin, probably Sanyo's fault). So I can start stacking dominos using my batteries once I upgrade. Lucky GH1 will always be my B-cam.
3) Video for GH2 is 24Mbps/24p, your GH1 is hack to 40Mbps for a reason... Cos we just want to have a super decent broadcast quality using a DSLR and cos we are cheapskates. If you lower the bitrate then we will end up like Canon... I think your competitor (support video tethering).
For those that read till this portion, thank you and have a cuppa joe, you need it.
Those that fell asleep, please wake up, sleeping on the keyboard is bad for the face.