These have been wrong before (see the Pitt rumors, the Missouri report) but this one is gaining steam and has been reported multiple times. From 810 WHB in Kansas City:
The Big Ten Conference has extended initial offers to join the league to four universities including Missouri and Nebraska from the Big 12, according to multiple sources close to the negotiations.
While nothing can be approved until the Big Ten presidents and chancellors meet the first week of June in Chicago, the league has informed the two Big 12 schools, Notre Dame and Rutgers that it would like to have them join.
The report goes on to explain that how far the Big Ten will go depends on Notre Dame. If Notre Dame takes the offer, they'll go to 16 teams. If they do not, they'll make a decision to hold steady at 14 or move forward with two more teams.
The important thing here is that the four schools they chose (Missouri, Nebraska, Notre Dame, and Rutgers) don't interfere with the ACC's potential Super-ACC plan. The ACC is far enough behind as it is; it's time to get proactive. If the Big Ten goes to 14 and the ACC remains without Syracuse and Pitt at the very least - they're great fits - then I'll be disappointed.
Seriously, if the ACC wants to do this - something to this scale may not be necessary, but it's a possibility - the Big Ten has not stopped them. The best fits all along have been Syracuse, Pitt, UConn, and Rutgers. Rutgers will jump ship if they choose to, but the other three remain. A team like West Virginia, Louisville, or ECU is a possibility, even though they may jeopardize the conference's academic prestige.
This will be an interesting shakedown. If you became ACC Commissioner today, what would your plan of attack be?