Turn-around time has been really bad for me for two distinct problems with my MacBook. First, the LCD backlight went out, and the local Apple Store had to ship it to a service center, which resulted in a 4 day wait to get it back in my hands. Then I had several keys mysteriously stop working - they couldn't figure it out at the store, so it was another week waiting for it to come back.

Another upside for Apple with these ultra-portables is that AppleCare sales will probably increase significantly.