Serious Eats: Talk
Harold McGee Says All Heated Oil is the Same?
There's an article behind the NYTimes' registration wall in which McGee and company test 15 oils, from canola to high end extra virgin olive.
(It's at http://www.nytimes.com/2010/11/17/dining/17curious.html and if you copy that into Google first you will be able to read the article without registering.)
The takeaway is that, once heated to typical cooking temperatures, no experts in blind testing could tell the oils apart; they all tasted "like popcorn".
The only part that struck me funny was his conclusion, where instead of recommending using extra virgin olive oil only for finishing and cheapo oil for everything else (as his introduction led me to believe) he basically just says "use what you want" for cooking, which seemed awfully wishy washy to me.
Have I read it wrong?