3dmodelerguy, if you mean keeping people from stealing intellectual property, the DVCSs generally ignore the problem completely, and leave it up to you figure out how to keep the unwanted people away.

If you mean, how do I keep people from vandalizing my repository, then the answer is that the publicly available repository is almost always read only. People can copy it and screw up their local copies as badly as they want, and no harm happens to you or your repository.

...

Another nice things about distributed repositories, is that they make making backups easy. You simply clone the thing, like everyone else does that wants to work on it. No need to make sure nobody changed anything while you were copying, leaving you with a broken and inconsistent backup.

In fact, you can practically get away with not making backups at all. If your server explodes, you can make a new empty repository on the server, and push your local repository into it. If you didn't have the most recent copy, that's fine, the next person to push that does will unwittingly restore any missing history.

Repairing a subversion repository isn't nearly that painless.