Seth Godin recently posted on the infamous "10,000 hours" that Malcom Gladwell mentions in the book "Outliers" -- his point is that the 10,000 hours to become an expert doesn't seem to hold up.
Couple comments on this. This seems to be a common misunderstanding of the orignal research completed by Don Norman. It's not enough to just do something for 10,000 hours and become an expert at it.
It takes two additional components for the hours to be meaningful -- it requires deliberate practice & objective feedback. Deliberate practice means that you're challenging yourself to improve, correcting errors and practicing at an appropriate level of difficulty. Objective feedback means that you have an understanding of what good and bad is. I would bet that 1,000 hours of deliberate practice is worth more than 10,000 hours of rote repetition.
Also, Seth seems to equate expertise with commercial success. Is Britney Spears an expert at singing, or is she a marketing success that happens to sing? There seems to be a difference. 10,000 hours rule is for people that want to master a craft that can be practiced. And in these cases the research is solid.
But, the reality is that there are exceptions. Picasso didn't practice 10,000 hours, but he was a once in a century talent when it came to painting. Cezzanne easily practiced 10,000 hours. He only became an expert through deliberate practice of his craft. His early paintings sucked.
There are always exceptions to every rule, but if you want to rise to the top your field in your chosen craft -- 10,000 hours isn't a bad goal to set, but what's just as important is the quality of your practice. Are you challenging yourself to improve, or merely repeating what you're good at?
Although, I do agree with Seth on one core point -- 10,000 hours doesn't necessarily equal success.