A recent article in the Wall Street Journal claims the Slushpile is dead.
Before you gasp with shock and dismay, be very aware that this claim applies to the book market, NOT the short-story market. The slushpile is still the bread and butter of most short story markets.
The following article [link] is a response to that WSJ article.
The Slushpile Is Gone: What Ambitious Writers Must Do
Be aware that it's pointing a finger at writers wanting to sell a book, but it has some good advice for short-story writers too.