Sinatra up and running - WHY WAS MY ORDER DELAYED?

I'm getting used to that capitalized phrase...
I ordered the book in April.
But I keep getting this sort of thing:

<snip>

We're writing about the order you placed on April 01 2011 (Order# xxx-xxxxxxx-xxxxxxx). Unfortunately, the release date for the item(s) listed below has changed, and we need to provide you with a new delivery estimate based on the new release date:

 Alan Harris "Sinatra: Up and Running"

   Estimated arrival date: December 16 2011 - December 29 2011

We apologize for the inconvenience caused by this delay.

</snip>

At this rate I won't receive it until April next year.