I recently upgraded my dokuwiki to the latest version (2009-02-14) from the previous stable release (not RC) and found that when I create new pages the link color fails to change with the change in existence state to reflect that there is now a page created for the link.
I tracked it down to the cache failing to update properly. In the documentation about the cache it states that the XHTML cache will update whenever the existence state of an internal link changes. The XHTML cache does not seem to hold the link existence state though. I manually purged the XHTML cache and it did not fix it. It only was fixed when I purged all the cache that it updated. I also tried clearing out the /data/cache folder and it did not fix the problem.