After Petabyte (Pb) comes an Exabyte (Eb), followed by a Zettabyte (Zb). Wikipedia does a good explanation, as always.

Regarding the editorial, it's an interesting subject, and lots of companies will find their own answer. What interests me most, though, is the aspect of backing all this data up, because backup technology (or more precisely that related to backup speed) doesn't always seem to keep pace with hard disc storage capabilities.