I noticed this at work today, but it still happens now i'm at home. It's on the 24" iMac page in the UK store (not tried any other.) The standard config, 1GB wired peripherals is £1349, so the "popular" config should be +£120 for the RAM and +£40 for the wireless keyboard and mouse. Yet when the popular config is clicked the price DECREASES by £50! I'm not sure if they've messed up or if it's a hidden deal!