Acer has already annouced there one, now Zotac are joining the fray.

http://en.expreview.com/2009/04/20/zotacs-atom-based-m-itx-mobos-for-ion-platform-in-the-works.html

HTPC dream; cheap, small, quite, efficient and powerful enough (thanks to the Dual Core Atom + nVidia 9400M) to handle most of our HTPC needs.

Only issue I see is since this current batch only have a mini PCI express port we're going to have to rely on USB DVB-T tuners. There are a few mini PCIX cards, but not sure how many have dual or more tuners.

Still, a very good step in the right direction.