Basically, all the celebrity hosts were asking Vince if the rumours about Bret Hart returning to host RAW were true, Vince said no for a while before getting pissed off and inviting Bret Hart to host.
So, on the next RAW, Bret came out and immediately called out HBK, after talking about Montreal for a while, they hugged. HBK left the ring and Bret then called out Vince who didn't show. At the end of the show, Vince called Bret out instead where he described Bret as "the best there was, is etc" before they also hugged. However, a few moments later, Vince kicked Bret in the stomach!
After Cena challenged Vince about the way he treats his wrestlers in a good promo, and called him a coward, Vince was persuaded to invite Bret back to give him a chance to ask why Vince did what he did.
Bret returned and he and Vince had a heated discussion which ended with Vince telling Bret that his dad Stu will never be inducted into the HOF. Bret snapped and began to beat down on Vince before Batista came out and attacked Bret allowing Vince to spit in his face. Cena came out for the save but after RAW went off the air, Batista snuck back into the ring and laid out Cena.
Cena/Bret and McMahon/Batista then had a couple of confrontations over the next few weeks. As Bret was leaving the arena after his "farewell" to the fans, a car reversed into his, breaking Bret's leg.
Last night on RAW, it was Cena vs McMahon.