But they subpoenaed people before, and even Harriet Meiers asserted some kind of weird personal executive privilege and just didn't show. With a DOJ not permitted to serve subpoenas, they become toothless.
But David Kurtz over at TPM points out a little wrinkle:
The committee is especially interested in Rove's involvement in the prosecution of former Alabama Gov. Don Siegelman. In conjunction with issuing the subpoena to Rove, the committee released a letter from the Justice Department's Office of Professional Responsibility confirming that it has launched an investigation of "allegations of selective prosecution relating to the prosecutions of Don Siegelman, Georgia Thompson, and Oliver Diaz and Paul Minor."
Now that's a horse of a different color.