How does the keypool feature work and why is it safer?
This gives a bit of info: http://bitcointalk.org/index.php?topic=1414.0
Among other things, a key pool means that you are more likely to be able to recover your wallet from an older backup.
Previously, this scenario
- send some money
- lost your wallet
- restore from older backup
might result in you losing all your bitcoins, even the ones you did not send.