Apples and oranges

Comparing David Frey's Canon T2i to my Panasonic GH1. We didn't even try to color-match the two cameras. Here is an un-color-corrected frame from each camera. We are at the same aperture... I think... f2.0?

Andrew Langton with the GH1 and a 35mm S.S.C. lens (I think).

The picture is clearly bluer in the T2i. That's because we didn't bother to color-match the cameras.

Canon T2i with newer Canon 50(?) mm.

The bigger difference to me is how the two cameras handle flares. That's probably mostly a matter of the newer lenses (like Dave has) not losing contrast as much and not having those distinct "rings" you get off the older lenses.
The Panasonic GH1 also has flare "spikes". I think that is the camera itself and the way it handles highlights.
Overall, to my eye, this footage from each camera is color-correctable into the same world, making the GH1 and the Canon T2i compatible for multi-camera shooting.
And lastly note that the GH1 is a "four-thirds" camera while the T2i is APS-C — which makes the same length lens on the GH1 seem "longer" than what it would be on the T2i.