I shot the dim-lighting test (also known as the rock-concert test) in a windowless room with a single lamp on. None of the phones performed particularly well in this test, but a clear winner--and a clear loser--emerged.
First Place: iPhone 3GS
The iPhone 3GS handled colors and light balance the best out of the four phones. Even so, it was still fairly hard to make out the Ferris wheel's details or the faces of the people in the photo. Motion was still a bit sticky, as well.
Second Place: Google Nexus One
All of the Nexus One's videos had an orange/yellow cast to them, but overall this phone captured the most vivid colors with the sharpest detail. The video still had that weird flickering effect, however, and I noticed the same issues with motion as I did in the bright-lighting test videos.
Third Place: Palm Pre Plus
Color-wise, the Palm Pre Plus's videos looked muddy. The train and its tracks blended right into the dark tablecloth, and the Ferris wheel looked like a giant blurry blob. You can make out the faces of the people in the photograph, but their facial details are completely washed out.
Fourth Place: Motorola Droid
The Droid, by far, had the hardest time with dim lighting. Videos came out very dark with a greenish tint; they were so dark that the train completely disappeared and the faces on the photograph looked like black blobs.