I posted this yesterday over here, but here is again because I kind of put it in the wrong thread anyway...
I've got something that should make your day. Original source is here.
This is a (perfectly safe) Shell Extension that will add "Delete SVN Folders" to your right click menu in Windows. Run it on any directory containing those pesky files.
Windows Registry Editor Version 5.00
[HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Folder\shell\DeleteSVN]
@="Delete SVN Folders"
[HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Folder\shell\DeleteSVN\command]
@="cmd.exe /c \"TITLE Removing SVN Folders in %1 && COLOR 9A && FOR /r \"%1\" %%f IN (.svn) DO RD /s /q \"%%f\" \""
To make this part of your build script copy that call to cmd.exe and execute it.