One of the most interesting things Dan Gilbert discussed was how we mis-remember the past to generally be more positive. I certainly agree with the premise - I believe it has been reproduced in the lab by psychologists, and is definitely something I can see myself doing. As Gilbert says, this memory is "lightly constrained by facts", but the brain seems to have evolved to not mind rewriting some details with ones it considers more preferable.
The part where I disagree, however, is when Gilbert says this "mis-rememberance" will be impossible because of all the extra data and photographs we have access to now. While it's true I have access to photos from ten years ago, I look at then very, very rarely, and I'm sure this will only decrease with time. Thus, a person who is willing to turn a blind eye to the less-ideal parts of the past (i.e. most of us) could simply "not check" what the truth really was, and continue believing their slightly re-written personal history.