This
article from Science News talks about an experiment from researchers in the UK where they stored a book on a DNA sequence.
The article says that one gram of DNA can store up to 2.2 milion gigabits of information (~468,000 DVDs).
Another advantage of DNA storage is that it can keep for thousands of years in a cold an dry environment. At the moment, it is currently only economic if storing information for 600 years and more.
