Depends on how much your shares are worth. Apple is already a large percentage of the S&P 500, so diversifying a relatively small amount wouldn't change much if you sold it for an index like the S&P.
Personally, I have a bit under $100k in Apple and plan on just letting it ride for now. But it will be one of the earlier sources I draw from when I need to sell. I suppose the base question is how much faith do you have in the company?