Judging by the model nomenclature, all three boards appear to feature Intel's H55 chipset. The H55M Pro houses VGA, DVI, and HDMI display outputs, while the H55M and H55DE3 are said to carry at least VGA connections. Naturally, those ports should be directly wired to the CPU socket to make use of Clarkdale's built-in graphics core.
All of the designs also include two PCI Express x16 slots, and the microATX models feature two sets of heatsink mounting holes -- not unlike the company's P55 motherboards, which have holes for both LGA 775 and LGA 1156 heatsinks. ASRock's H55M seems the most barren of the trio, with only four SATA ports and two DIMM slots.
Apart from features seen in the images, few details are known, but it's probably a fair assumption that ASRock's H55 motherboards will ship alongside Clarkdale in early 2010 at around $100 price point.