I have a 13' Mid-2010 MacBook Pro and I have had Lion for a few months now, i've recently noticed with the addition of my second display that my fans have been going crazy when i only have Twitter, Safari and Mail open and some other small apps like iChat. I've done a SMC reset, PRAM and all those reset's too and it just gets really loud. Also when the screen savers are on and I come back to the computer after 5 minutes of the screensaver running the fans are off and are really loud. I've tried the app SMCfancontrol to monitor the temp and it stays at about 122 to about 133 when i'm chatting on iChat and also when the screen savers are running.
Please, someone help!