Read this at a couple places

BloodyElbow has exclusive details on what now is becoming more than just speculation. Michael Rome of BE has the scoop.

First, I can say with 100% certainty that there are current negotiations for Randy Couture to return in November to main event, and that the current proposed opponent is Brock Lesnar. They can't get Fedor, too many issues to work out on short notice, and he has a US-only non compete with Affliction.

This will be a new contract, not a return to the old one. It will likely pay him more and give him more benefits, but it will lock him into the UFC for the long term. In exchange for signing it Zuffa would drop all breach of contract charges.
Dave Meltzer has started confirming things on f4wonline.com

A source close to Randy Couture has confirmed today that Couture is in negotiations with UFC for a new three-fight deal which would end the nearly nine month legal battle between the two sides.

If the deal is closed, and the source said they are hoping to conclude negotiations and announce the match sometime within the next week, Couture would face Brock Lesnar on 11/15, most likely in Portland, Oregon.

Couture was said to be hoping that if everything went well, the next two fights could involve Fedor, Nogueira, and/or Chuck Liddell. However, all previous hangups involving Emelianenko and UFC remain.

That will be the highest grossing PPV in UFC history if that fight goes down. I hope it does.