Story courtesy Strange Horizons via Boing Boing.
If you read the statistical analysis of this it will make your eyes bleed polynomials so I'm going to break this down to show the trends occuring in genre fiction.
Stand Alones, Sequels and Other books (factual books on science fiction, art books, etc) are trending upward or are stable. Collections and anthologies are going flat. Unless some smart person has a new way to present the anthology or collection...hmmm.
Stand alones and sequels dominate.
Standalones and sequels rule the abattoir here. Short fiction anthologies are actually trending down.
Looking at # of books published per year:
(Please go to the Strange Horizons link above to see the more detailed analysis and charting)
I would be interested in seeing a similar analysis performed on online book services (IPhone, Kindle) and Print On Demand publishing to further refine this data. Media distribution does make a difference, and I suspect (though can't confirm) there's more short fiction potential in those arenas (for what I'm going to assume are obvious reasons at least to this audience).