I weighed in this morning on the issue – that the primary results are a pretty good poll to suggest the condition of the electorate as a whole. And here is what Swing State Project says about our results.
But Seattle pollster Stuart Elway has a different view, expressed in this piece on Crosscut.
Finally, though, here is a spread sheet prepared by Greg Giroux at Bloomberg that compares the 2008 Washington Congressional primary to the general election. He tallies all votes for each party in the primary and compares it to the percentage spread in the general election. It is nearly dead on, except in the 8th Congressional where Darcey Burner fell off by 3 points.