Having slogged through the 3 volumes of the 3rd Edition of TAOCP, I came away with 2 impressions: 1) How did Knuth work art into the title? 2) Disappointment that he took so long coming out with subsequent volumes. So long, that I no longer care about reading the subsequent volumes.
Watched his Christmas tree lecture, and he said the hardbound vol. 4 (not the facsile) will be out in 2010. I consider that the true vol.4...only, what, 5 or 6 years later than he originally proposed.