Basically, yes. Back to my Mac forms an IPv6 based IPsec VPN mesh. Meaning any of my systems with my credentials can see any other systems, similar to Hamachi. This includes the Time Capsules. It's not an automatic offsite backup out of the box, though it does provide me the ability to script a backup to work just as if their Mac was on my LAN, with file sharing turned on but not exposed to the world. Automatic hourly backups are still handled by Time Machine to their Time Capsules.