OK, I know this post is a bit late but I only found out last night when my flatmate told me, that Prime is now on Freeview (both FreeviewHD and Freeview).
There are posts about that in the geekzone Freeview forum but I only read the HTPC forum and I can't see anyone else has made that announcement so I'm making it now.
http://www.stuff.co.nz/technology/digital-living/2757359/Freeview-expects-boost-with-Prime/
I successfully tuned it into my STB last night (will do MediaPortal tonight), it's only broadcast at 576i which is a shame cos I was hoping to get All Blacks replays broadcast in HD...
-Matt