Salesforce.com CEO Marc Benioff just tweeted that his keynote has been cancelled by Oracle. He wrote: “I don’t know why….your guess is valued. Just cancelled. That’s all we know.” In lieu of his keynote, he’s invited people to join him at St. Regis AME Restaurant at 10:30 AM tomorrow instead.

Here are the tweets, along with some select commentary:

Services Angle

The rivalry between Benioff, who was an executive at Oracle under Larry Ellison, has long been heated. But Benioff has appeared at Oracle OpenWorld every year. Salesforce.com is a major Oracle customer. Salesforce.com’s services, including its flagship CRM service and its Database.com service are both based on Oracle products.

It’s too early to say what this will mean for the rivalry between the two companies and whether Salesforce.com remains an Oracle customer for much longer. Salesforce.com presumably remains an Oracle customer for the same reasons so many others do: once committed to the Oracle platform it’s difficult and expensive to move off it. But Salesforce.com must have had an exist strategy already in place, and this disrespect may be the final straw.