I have been using Apple’s Color to grade the Biking DVD I am working on and have been getting on quite well with it.  Problems started happening when I had sent my rendered files back to FCP and wanted to make corrections.  The normal route for this is to open the Color file again, make the corrections, render them out, and then they should automatically reconnect in FCP.  I tried this method but the updated graded render files were not updating in FCP.  It’s only when you restart FCP that it will see the newly rendered files and connect to them.  A simple solution, but not really that obvious.  Note that you should also not re-use the Send To command once clips have been re-rendered.