Yeah, I challenge ANYONE to tell me how having a 10MP camera made him take better pictures OR take pictures he wouldn't have been able to with a 6MP. Oh, and cropping does not count.
For that matter, I'd hazard a guess for most people the limiting factor is their technique and the quality of their glass - their photos on a 10MP sensor don't have any more detail then they would if it was a 6MP sensor.