I have the late 2008 MacBook Pro with the removable battery so I don't know about the situation of the integrated battery in the newer MacBook Pros with the extended batterylife.
However, I just looked on this website and found...
(Images probably are from iFixit.)
... Didn't somebody say that the battery was unremovable and had to be replaced by Apple if you wanted to switch it out?
However, I just looked on this website and found...
(Images probably are from iFixit.)

... Didn't somebody say that the battery was unremovable and had to be replaced by Apple if you wanted to switch it out?