The cause of the crisis? A bad harvest. After heavy rains in the fields, the pumpkins rotted before they could be saved. And while it's unlikely that you'll see canned pumpkin selling on eBay, the shortage has already affected many grocery stores -- and those who aren't sold out are expected to be emptied of canned pumpkin by Friday.
The upshot is that there's always next year if you haven't stocked up. If you've just got to have that custard pie, however, try using pureed butternut squash in place of pumpkin in your recipe. It's a little more work (canned squash is not an option), but you can be proud of the effort and it'll taste nearly the same. Sweet potatoes are a wonderful substitute as well, but you'll need to find a recipe for sweet potato pie.
And if anyone wants to place a bid, I've got a can of pumpkin sitting in my cupboard.