CM Punk's appearance in walking Chael Sonnen to the ring at the next UFC on FOX from Chicago is not a deal made between UFC and WWE, but something Sonnen and Punk put together on their own.

This is not a promotional agreement between the companies as part of a working agreement, or a plan to set up Brock Lesnar's return to WWE.

WWE and UFC have worked together in the past.

When Ken Shamrock first came to the then-WWF in 1997, WWF licensed footage of him fighting in UFC to explain to their audience who he was. When Brock Lesnar made his debut for UFC, UFC licensed footage of Lesnar in WWE for use in commercials promoting his PPV debut, a deal that was put together by former WWE Executive Shane McMahon.

Dana White has always spoken highly of Vince McMahon and WWE and visited with him at WWE HQ in Stamford, CT earlier this year.

The two sides working together isn't outside the realm of possibility, but in this case, that's not what is happening.