Warren Buffett's growing cash pile speaks volumes about the current state of the stock market.One of the qualities that makes Warren Buffett one of the most successful investors in history is his patience.He noted the importance of waiting for opportunities in his most recent letter to Berkshire Hathaway (BRK.A 0.70%) (BRK.B 0.68%) shareholders."Understandably, really outstanding businesses are very seldom offered in their entirety, but small fractions of these gems can be purchased Monday through Friday on ...