SVK comes in handy whenever you want to work on a project whose files are kept in a remote Subversion repository, but you don’t have network access.
Sure you could just hack away and commit once you’re online again, but this way you lose all the things you are using a version control system for: commit/rollback, changesets with meaningful descriptions, branches and so on.
Besides that, another huge plus of svk is the complete lack of any metadata inside working copies - no more .svn directories getting in your way!
