Sigma today published a list of all Sigma lenses conforming to the Four Thirds standard digital camera system. The Four Thirds system is used by a variety of digital SLR camera's including those recently produced by Olympus, Sigma, Panasonic (Lumix DMC-L1), and Leica (Digilux 3). The standard dictates the size of the lens mount and the distance from the image sensor and lens-camera communication. It also standardizes the sensor size and aspect ratio at18x13.4mm and 4:3 respectively. The Sigma lenses currently using the Four Thirds system include the:

18-50mm F2.8 EX DC MACRO
18-50mm F3.5-5.6 DC
18-125mm F3.5-5.6 DC
55-200mm F4-5.6 DC
50-500mm F4-6.3 DG
30mm F1.4 EX DC HSM
105mm F2.8 EX DG
150mm F2.8 EX DG

This list can also be found here.