They may be hardy in "European" winters, but I doubt they are hardy here in the states with our winters. I'd like to know more about them. The website doesn't say how hardy they are.

All the web sites/photos seem to be from the same marketer. I found this interesting article about them by Graham Rice of the RHS.
Remy

Here is a link that might be useful: Wintunia Article

I'm entirely willing to wait until these plants have proven themselves through a few actual winters (and not just the ones in Great Britain or coastal U.S.) and hot summers and then think about how badly I want/need a perennial petunia when there are hordes of cheap annual ones in every color and style imaginable (and which I hardly ever grow anyway).

After the Coreopsis 'Limerock Ruby' debacle (in which a variety supposedly hardy to zone 4 proved unreliable anywhere above zone 7) I think a lot of gardeners will be wary about forking over significant amounts of money for dubiously hardy perennials.