All three motherboards are based on Intel's ATOM D525 1.8GHz dual CPU paired up with Nvidia's ION, and all are mini-ITX form factors. Of course, we are talking about next-gen Nvidia ION GPU and this one comes with 512MB of DDR3 memory in Zotac case. The rest of the features include two SATA 3.0Gbps ports, Gigabit Ethernet, integrated 802.11n WiFi, Dual-Link DVI-I and HDMI outputs, and integrated 6-channel audio.
The ION-ITX R series features two DDR2-800 DIMM slots with support for up to 4GB of memory, has one PCI-Express x1 slot, eight USB 2.0 ports (6 on back panel and two via pin header) and basically we are talking about a plain mini-ITX motherboard. The ION-ITX S series is pretty much the same thing except for the fact that this one has two USB 3.0 ports and uses DDR3-800 SO-DIMM memory instead of the DDR2-800 DIMM on the R series.
The ION-ITX T series is a bit different as this one features two DDR3-800 SO-DIMM slots with support for up to 4GB of memory, single PCI-Express x4 (open-ended) slot, two USB 3.0 ports and six USB 2.0 ports, on-board DC-DC power supply with bundled power brick, so basically you get a mini-ITX motherboard that comes with its own PSU.
Unfortunately, the precise availability date or the price haven't been announced but we're guessing that these will show up pretty soon.
Zotac ION-ITX R series
Zotac ION-ITX S series
Zotac ION-ITX T series