I have just "downgraded" my macbook pro which i purchased lion on, to a macbook air which doesnt have lion. Can i somewhow upgrade to lion for free as i had already purchased it on my old mac?
yup if you use the same apple id as you did when first purchased it it will be in your Purchased tab, if for some reason its greyed out thinking its still installed, close the app store, hold option and re-launch the app store, keep holding option and click the purchased tab and it will be available to re-download