Wojnarowski was originally offered a cool $400,000 (of which he received $140,000), but his repeated delays caused Penguin to reduce the total advance to $325,000. Now, over three years later, they've canceled the book and are taking Wojnarowski to court to recover the $140,000 they already paid him.
I wish I could say this kind of story was uncommon, but honestly, the only unusual aspect is the filing of a lawsuit. Books are delayed by months (sometimes years) all the time, and failure to meet deadline (sometimes more than once) is not unheard of. I think, however, that publishers' patience is particularly short in the midst of the recession, so I wouldn't be surprised if they were to become even less lenient about missed deadlines, particularly for books bought for six- or seven-figure advances.
The reasons for delays can range from author laziness to the publisher's disapproval of various drafts (that is, sending them back for rewrites) to changes in current events that warrant substantial revisions (generally affecting only nonfiction). Remember, too, that most advances are cut into pieces: often one installment is paid on signing, another on receipt of the manuscript by the publisher, and occasionally a third on or around the date of publication. If you're getting $400,000 and you've already gotten $140,000 just for signing a piece of a paper, one can see how your motivation might be temporarily shot.
That said: this business is slow enough as-is, so as début writers who always want to make the best of impressions, it's in your collective best interest to get your manuscripts and revisions delivered on time. Always be professional, always be on time, and always ask your agent or editor if you have any questions about deadlines, timelines, or any of the other myriad -lines to which you might be subject.