Yup...
But either is considered valid nowadays in the UK. In fact I seem to remember that kids are now being taught the z version in schools now because the American spellings are so commonplace.
If you look at the history (and the number of edits I made this morning), a good half of those are correcting my own typos and spelling mistakes. So if anyone finds ones I missed, please feel free to castigate me. I know better and deserve it
