a while since AOpen made a consumer level product, but its latest barebone might appeal to those looking at a compact low power HTPC box, but don't mind paying a bit of extra for the pleasure of having a mobile CPU in it.
The XC Encore OE700 as it's called features the Intel GM45 chipset and as such you'll need a Socket-P mobile Core 2 or Celeron processor, all of which are sold at a premium over cheaper desktop processors. The system is also limited to using SO-DIMM memory, but this shouldn't be a problem as SO-DIMM's generally doesn't cost any more than desktop memory.
Size wise the XC Encore OE700 measures 200x321x106mm (WxDxH) and it houses a mini-ITX motherboard, There's room for a notebook style optical drive, although you need a slot-loaded model, as well as two 3.5-inch drives. One limitation here is that all drives has to use SATA interface, as the motherboard doesn't support IDE. The board also has two mini-card slots for expansion cards, such as WiFi or TV-tuners.
Connectivity wise you're looking at a DVI and HDMI port, eSATA, four rear USB 2.0 ports and two front USB 2.0 ports, Gigabit Ethernet and 7.1-channel analog audio with S/PDIF in and out. There's also a front mounted VFD with Media Center integration. The XC Encore OE700 uses an external power brick which is rated at 135W.
No pricing or availability date has been announced, but we'd expect the EX Encore OE700 to pop up at various system integrators under various names within the near future.
You can find the product page here