While setting up a CruiseControl.NET server for a project here at Falafel I ran into this error:

svn: Working copy '.' locked
svn: run 'svn cleanup' to remove locks (type 'svn help cleanup' for details)

After executing svn cleanup from the command line numerous times to no avail I finally realized the problem was a missing <workingDirectory> node for the project in the ccnet.config file. Well, I won't be making that mistake again.