Marc Benioff, CEO of, confirmed today at the company's annual Dreamforce event in San Francisco that he has not been invited to Oracle Open World, later this month, after the companies came to blows last year.

Tensions between the two rivals increased in 2011 after Benioff posted some disparaging comments on Twitter during Larry Ellison's keynote at Oracle Open World.

Speaking today at Dreamforce, Benioff said: "We are not invited back to Oracle Open World this year for some reason, I don't know why?"

Following 2011's cancellation, Oracle offered Benioff another time slot on Thursday morning - when he was on his way to speak at another event in Ohio.

Using Twitter, he drummed up enough interest to hold a rogue keynote address to an overflowing room at a local San Francisco restaurant at the time he had been originally scheduled to speak.

"Larry just cancelled my keynote tomorrow!" Benioff Tweeted, inviting people to join him at the local restaurant instead. "Beware of the false cloud," he added. In another message on Twitter, Benioff said "The show must go on! Sorry Larry!"

Benioff also sent a message to Michael Dell, CEO of Dell, saying that he looked forward to seeing him and hearing him talk at Dell World. "OK, please don't cancel me like #oow11."

Speaking this week in San Francisco, Benioff took the opportunity to take another dig at Oracle's cloud offerings and said that the industry should be looking to start-ups for innovation.

"I have always thought that competition is very healthy. We need more of it, we don't need less," he said.

"You can see how [Oracle] continue to resist even multi-tenancy and shared systems, they are kind of moving towards it, but they are kind of not. I think they've really done a disservice to themselves."

He added: "But I think it's the start-ups that have been so exciting. We know that the young companies, a number of which have now been acquired, who have copied our model. We pioneered it, but we want to see the whole industry move to this new technology model."

In other news, Salesforce unveiled a number of products for mobile computing, social collaboration, social analytics and marketing this week.