It's been reported that Seve Ballesteros underwent a surgery lasting several hours (anywhere from 7 to 12 depending on which report you read) to remove as much of the brain tumor as possible. Reports have not indicated if cancer is present and have only speculated on what further treatment may be needed. Some reports indicated that Seve was conscious and responding well after the surgery. I hope for the best for Seve and I think of him many times throughout the day.
Here is a good article from Sporting Life that includes some insight that you might not have previously had about Seve and his affection for golf and the up and coming players.