I came across this today on facebook, the ability to download your entire Facebook history.
It can be found under:
Account > Account settings > Download your information
I expected the download to be quite large, and perhaps bigger than the 530MB that it was in the end (this took about 4 hours to generate, I then got an email to say it was ready with a download link)
The zip file itself contained and index.htm file and various subdirectories containing all photo albums (all neatly indexed), all videos and all wall posts etc. It was kind of interesting to look back through it all and could be quite handy for somebody who doesn’t do backups of photos etc. Although the images downloaded are obviously the resized ones from the uploader.
More information can be found here.