The rumor on ESPN is based around this article from the Chicago Sun Times which says the following:
If athletic director Jack Swarbrick decides Weis' Notre Dame career is over after his fifth season, a source said Oklahoma coach Bob Stoops and Iowa coach Kirk Ferentz will be in the mix to replace him. The source said Stoops has told confidants he would be interested in talking to the Irish.
The only thing that makes these rumors a little juicier is that Stoops has been receiving a lot of criticism this year, as has the coaching staff (Kevin Wilson in particular). For what it's worth, Jim Harbaugh's name also popped up today in rumors about Notre Dame.
One thing seems likely - the Irish are tiring of Charlie Weis, and they have blocked their plane on Flight Aware so people can't see who they may or may not be flying into South Bend.