As the estimated delivery date of March 5/6 had passed, I checked Where's My Stuff? to see what was up. The CSS book is now to be delivered on April 11/12; I assume the UK publication date has been pushed back. However, my other book has just vanished into the ether. It hasn't been dispatched and it's no longer showing up on the order. It's not in Open Orders or Completed Orders or All 2004 Orders. It's gone, man.
I'll have to wait until I get home and can check my bank statement, but I'm pretty sure I've already been charged for it, too. I rather hope I have; at least then I'll have proof that I didn't imagine ordering it.
I'm really sick of Amazon's ceaseless cockups. If this keeps up I may start buying my books from actual bookshops again.