Are premium templates compatibile with any of this portal systems?
What about Wedge? Its also compatibile with this new SMF clone?
If by compatible, you mean they install properly and are displayed on the portal page then they are compatible, the only issue worth mentioning is that with SimplePortal, the left-side of the title bar usually defaults to the default theme, which can be corrected by simply copy pasting the portal.css in the default theme directory to your custom theme's directory (in the css folder).
As for Wedge, by my understanding, a lot of the legacy code in SMF has been removed in Wedge and a lot of the layouts have been changed to display differently to the current setup that SMF uses. I do not think these themes will work on Wedge, as none of the SMF mods (that aren't already supported by Wedge authors) will not work on Wedge.
Making themes for Wedge will be a lot easier though, because they've implemented CSS substyles (which is very interesting and promising after you've read more about it) so it will not be long before some decent Wedge themes start surfacing once Wedge has been properly released.
I'll leave any other information that needs to be stated up to Arantor, as he is part of Wedge's development and can clear more things up for you if you have any more questions.