This is the error I get
# yum update
Loaded plugins: refresh-packagekit
Error: Cannot retrieve repository metadata (repomd.xml) for repository: updates. Please verify its path and try again

from the add/remove software that is what I get:

Error Type: <class 'yum.Errors.RepoError'>
Error Value: Cannot retrieve repository metadata (repomd.xml) for repository: updates. Please verify its path and try again
  File : /usr/share/PackageKit/helpers/yum/yumBackend.py, line 2150, in <module>
    main()
  File : /usr/share/PackageKit/helpers/yum/yumBackend.py, line 2147, in main
    backend.dispatcher(sys.argv[1:])
  File : /usr/lib/python2.5/site-packages/packagekit/backend.py, line 605, in dispatcher
    self.dispatch_command(args[0], args[1:])
  File : /usr/lib/python2.5/site-packages/packagekit/backend.py, line 566, in dispatch_command
    self.search_name(options, searchterms)
  File : /usr/share/PackageKit/helpers/yum/yumBackend.py, line 344, in search_name
    self._do_search(searchlist, filters, key)
  File : /usr/share/PackageKit/helpers/yum/yumBackend.py, line 310, in _do_search
    self._do_meta_package_search(fltlist, key)
  File : /usr/share/PackageKit/helpers/yum/yumBackend.py, line 282, in _do_meta_package_search
    self._show_meta_package(grpid, fltlist)
  File : /usr/share/PackageKit/helpers/yum/yumBackend.py, line 418, in _show_meta_package
    grp = self.yumbase.comps.return_group(grpid)
  File : /usr/lib/python2.5/site-packages/yum/__init__.py, line 607, in <lambda>
    comps = property(fget=lambda self: self._getGroups(),
  File : /usr/lib/python2.5/site-packages/yum/__init__.py, line 548, in _getGroups
    if not repo.ready():
  File : /usr/lib/python2.5/site-packages/yum/yumRepo.py, line 318, in ready
    return self.repoXML is not None
  File : /usr/lib/python2.5/site-packages/yum/yumRepo.py, line 1241, in <lambda>
    repoXML = property(fget=lambda self: self._getRepoXML(),
  File : /usr/lib/python2.5/site-packages/yum/yumRepo.py, line 1237, in _getRepoXML
    raise Errors.RepoError, msg