In 2007, Viz Media released volumes 16 through 27 of Naruto all within four months of each other in North America in a campaign they dubbed "Naruto Nation". According to the release listings of Simon & Schuster, a Viz distributor, they'll be doing it again, but this time all in three months. Volume 33 of Naruto will release normally on December 3rd, but after that, the next 11 volumes are being released a few at a time.

The release dates are as follows:
Volumes 34 through 37: February 3rd
Volumes 38 through 41: March 3rd
Volumes 42 through 44: April 7th

Source: ANN

Special thanks to Baby_Naruto for the tip.