Under Windows 7, how can I delete a folder whose name ends with "..."?

You should be able to delete it using the "rd" command, but with a different syntax:

rd "\\?\DRIVELETTER:\FOLDERNAME"

The FOLDERNAME placeholder should, of course, be the actual name of your problematic folder, dots included.

If the directory is not empty, you would receive an error message. To force deletion of the directory and its contents, you can use the /s switch:

rd /s "\\?\DRIVELETTER:\FOLDERNAME"

The "\\?\" path prefix is documented here, under "Win32 File Namespaces":

http://msdn.microsoft.com/en-us/library/aa365247(VS.85).aspx

The only way I was able to remove a test directory with a similar name was to use Cygwin.