Remember, the original purpose of this was to encyrpt mySQL dumps on a daily basis and send them offsite for backup purposes.
If it involves sending the key to the backup site, then I'd need a secondary encryption system such as PGP to send the keys securly, in addition to a way to tie each unqiue key with each unique data file. Murphy's Law says that when you try to decrypt one of 365 daily files in a year, its going to be that days key that you've misplaced.
It seems to me for this to be practical, you would want to avoid having to track randomly generated keys to try and decrypt your files at some future date. My limited understanding is that Public key encryption is much more processor intensive than private key encryption so this is also a concern given the large size of mySQL dumps and the possiblility of simply PGPing the mySQL dump.
Filmo the Klown