Japanese website DC-Watch has tested the Sigma DP2 against the Nikon Coolpix P5000 (yes, it's an older camera), and posted the comparison pictures and their computer-translated findings. The sample pictures are available as full-size JPEG.
RAWsumer reviews at the Compact Reviews Organizer
CANON: G11 S95 G10 G9 S90 SX1is
PANASONIC: LX5 LX3 LX2 FZ50 FZ100 FZ40/FZ45 FZ38/FZ35 FZ28
RICOH: GRD III GRD II GX200
SIGMA: DP2 DP1
NIKON: P7000 P6000
CAMERA DIARIES: Panasonic LX3 Canon G10