Finally! The truth about thread count.
In a quality product, the incremental comfort value of increasing thread count over 300 is very little. A 300 thread count can feel far superior to a 1000 thread count. Thread count has become a simple metric used by marketing people to capture interest and impress with high numbers. The problem with mass produced high thread count sheets is that to keep the price down, important elements of quality must be sacrificed, meaning in the end the customer gets a product with an impressive thread count but that probably feels no better (or even worse) than something with a lower thread count.
I am hoping that John Hodgman will shed further light on the thread count controversy (working title: CountGate) in his new book, More Information Than You Require.
Update: Even more about thread count. (thx, jeremy)