Over the past few weeks SourceForge.net has been moving projects from cvs.sf.net to projectname.cvs.sf.net. Not wanting to delete my currently checked out copy of pkgsrc-wip and check out again, I needed to update CVS/Root in each checked out directory. Neil gave me this useful snippet to accomplish exactly this:
find . -type f -name "Root" | grep "/CVS/" | xargs sed -i -e 's/cvs.sf.net/pkgsrc-wip.cvs.sf.net/'

It assumes a sed which supports the -i option – NetBSD‘s doesn’t, so I used perl -i -p -e instead (I could also have installed textproc/gsed from pkgsrc, but I already had perl installed).