Unless you're talking about something subtle, the center dash in US and Canadian Imprezas look the same to me. Pictures:
2012 WRX and STI are unchanged from 2011.
A few weeks ago, I asked Japan Parts if there was a JDM A/V panel for 2012, like the one Subaru has for 2008-2011. They said no -- there's only a piece with the smaller 7" opening that fits on top of
the stock bezel. :yuck:
The picture I posted earlier of the Pioneer in a Canadian Impreza looks like a trim piece similar to the Metra and Scosche parts for 2008-2011. I think that's the best you're going to get for 2012 (and what I'm guessing will be the dash coming soon for 2013 WRX and STI). Or hazmat's and ashio's hack.