Oil spills have been around, yes, but none as big as this. Technology that works for smaller spills is being deployed, but it’s hard to clean up miles and miles and miles of beach with men and shovels, and it’s hard to clean it up when technology that does work is not deployed properly (link goes to video with strong, NSFW language). My own personal speculation is that “oil cleanup costs money, it doesn’t make money, so it’s best for the company to socialize the direct and indirect costs of cleanup and go on to more profitable activities, such as pumping more oil without obeying too many expensive safety regulations.” But that’s just me.
Also, BP is pumping a vast amount of “dispersants” into the water to make the oil break up and sink to the midstream, where it’s not as visible on beaches and they can deny that it’s even there. It’s sort of like a mix of oil and soap, which is pretty much impossible to separate. It’s not like you can just go suck up pure oil.