The 975 is slated to support Conroe however, the current 975 that is out now will not. The reason is, they do not have the lower voltage requirements for Conroe.
Intel is supposed to put out a revision for the 975 so it will support Conroe at its release. Keep an eye out for the revision. Additionally, they will be releasing a new chipset solely for Conroe and I believe that will be the 965.