I have the 2010 i7 unibody macbook pro, & read through mroogle about leaving it on all the time vs shutting down. It seems to be a toss up, but I did read cases for either way, one person said they were told by an apple care guy that starting up/shutting down puts wear & tear on the hard drive. another poster described after leaving theirs on for a few months, they found the outer casing had peeled away from the battery, from heat. I could leave mine on, however, my concern is my bedroom is in an old house with no insulation, which means the house is not so warm in the winter, & gets hot in the summer. My mac is in my bedroom, & my bedroom can get quite warm in the summer. Also, for protection of the body on my mac, I have a speck products rubber satin case on it too. I have it on a metal stand or laptop stand that has wire mesh. So in my case, would it be safe to leave it on all the time & shut down when I will not be home? or just start up/shut down every night after I am finished using it? with the heat in my room, I dont want the computer to melt or it's components to melt. Another thought, when I do more intensive tasks on it that kick up the fans, will the case & heat in my room become a problem?