I think what people have lost proportion with is just what you are getting for that money. About 2 years ago I was regularly hiring a Sony XDCAM HD camera the PDW-700, they cost something like £30-40K to buy! You couldn't buy one! In fact you could only afford cameras like the EX1 and EX3 (wow they disappeared fast didn't they!) The image was not as good as my 7D (although the workflow was far better). 2 years is not a lot of time to now be able to buy a camera far far better (the C300) for what is about a third or a quarter of that price. And that's the comparison that should be made, what these cameras cost compared to what similar cameras cost in the past. Not what DSLR's cost.
I think Andrew is right, for most of us Indie film makers it's the camera to dream about hiring for some projects but not one to buy. There's no way I could justify it. I paid back my 7D and 550D in a about a 2 months of camera charges for the production company I was working for, which was amazing. It would take a hell of a lot longer to pay back a C300. I think it has incredible virtues, but I can't justify it.
The FS100 has been getting a lot of praise recently (surprisingly), but I think there's a lot of issues for it. I hired it for a shoot for the 50FPS slow-mo (I now have a Nex-5N for that!) and I was really disappointed with it as a camera, clunky, rubbish for handheld with a very poor zoom lens on it and a laughable LCD, the results I got were almost always overshadowed by the 7D I used as B-cam. And the editing workflow was rubbish (with all the 50fps stuff). But it was okay because I was handing it back! The Nex is a wonderful camera, the results very cinematic and incredibly easy to use, with that E-mount to EOS adapter I think it'll be a serious proposition. And the slow-mo looks wonderful. The LCD is beautiful and people will not realise you are filming. Which is a real consideration as a Canon user these days!
The C300 will slot perfectly into the market and it'll do really well, I'll probably hire one in a couple of months (for a project it'll really add something to). I really think the codec, the form factor, the attractive price and the EF lens mount will make it sell by the bucketload. And the exciting thing for GH2 users is that their camera is not a million miles off in terms of image quality!