Production of United States Mint American Eagle Silver Proof and Uncirculated Coins has been temporarily suspended because of unprecedented demand for American Eagle Silver Bullion Coins. Currently, all available silver bullion blanks are being allocated to the American Eagle Silver Bullion Coin Program, as the United States Mint is required by Public Law 99-61 to produce these coins “in quantities sufficient to meet public demand . . . .”
On a personal note, I've noticed that my favorite silver coins (40% Kennedy half dollars) are less available on eBay in large lots than they were just a few months ago. Granted, you can still buy them by the bag at Apmex for the spot price of the silver contained, but just last Fall you could buy large lots on eBay and have them delivered to your door for 3-8% less than spot price.
Of course the pendulum can swing both ways, but it's pretty clear to me that it's swinging towards "less silver available" right now.