In light of Gawker's recent situation, how should you be salting passwords?

I figured I'd ask. We all know by now that Gawker has was compromised and it sounds like they weren't salting their passwords very well, or at all.

With that in mind, what is the proper way to do this? Is it fine to simply have a single, rather random salt used or should you somehow change the salt all the time? If the salt changes, how do you know how to compare it when they're logging in?