Jerry made an amazing comparison and posted it inside the dpreview forum. Here is his text and comparison:

I have recorded ’10 second’ samples using 3 cameras:
E-P1 & GF1 (PAL, AVCHD) & GH1 (PAL, AVCHD).

All records are in AUTO mode – by purpose! Goal is not to show maximum, best capability of each camera, but what will starting user get.

You of course can tune each camera, BUT general view WILL NOT CHANGE drastically.
(Anyway – see last sentence of this post!)

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Honestly speaking, I am surprised with GF1 results. I didn’t expect miracles with F/4.0 – no doubts, but I was expecting nice, pleasant results with F/1.7!

Plus – I was sure, that in SD resolution – there won’t be big difference against GH1.
It is not a case. GF1 looses a lot with GH1 in 720p.

It means that GH1 can maintain high ISO much more better in video.
At F/4.0 it is still useful in artificially lit room. GF1 is not.

Also GH1 in 720p is supposed to use 50 fps, and GF1 only 25fps. But it doesn’t change results…

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E-P1 is not so bad with F/1.7, but looses a lot with GH1 at F/4.0.

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GH1 – no surprise – for low light offers most, especially with FHD and in manual mode, where you can select aperture, speed & ISO.

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1. SD – 720p
2. FHD – 1080p

20mm @ F/1.7
E-P1 SD http://www.youtube.com/watch?v=YD9Jd2E9bvw
GF1 SD http://www.youtube.com/watch?v=k-SYtpbGahA
GH1 SD http://www.youtube.com/watch?v=hpxxJS0tDF8
GH1 FHD http://www.youtube.com/watch?v=gEgJYbbgO1k

7-14mm @10mm @ F/4.0
E-P1 SD http://www.youtube.com/watch?v=2MpE3k3dNUk
GF1 SD http://www.youtube.com/watch?v=dDQhmp6HlQI
GH1 SD http://www.youtube.com/watch?v=VUPrKRVLkcM
GH1 FHDhttp://www.youtube.com/watch?v=F7No6JrRUDU

7-14mm @10mm @ F/4.0 @1/6 sec @ISO 800
GH1 FHD MANUAL http://www.youtube.com/watch?v=EloB4SfEjI0