A couple of days ago, I bought an Apple TimeCapsule, in order to have a local backup of my Macs at home.
Once I set it up, I realized that, TimeMachine will not allow you to do encrypted backups on TimeCapsule! As I alway enable FileVault, and in general try to make sure all my data are encrypted, I was close to selling it on ebay, when I read this: Mac OSX Lion Secure Backup to Time Capsule with size limit.
It works. You only have to follow the instructions (quite simple), the first time, and then everything will work as normal.