PStwo harddrive added?

Some hardware hackers claim that they have figured out how to add a harddrive to the slim Sony Playstation 2. Is it possible?
Not for the faint at heart, but looks fun. I’d rather install this one for the regular Playstation 2 [warning of language].
Hackaday and Joystiq

Personal note: I might play with the Playstation 2 (regular) install seeing that I have about thirty plus games that I would like to keep but spinning those CDs/DVDs really scratch up the discs. So many fun projects, so little time.