Kodak has announced that "due to significantly decreased sales volumes," TXP (ISO 320) in 120 and 220 are to be discontinued in March.
This news isn't as significant as it might sound if you don't keep up with film. The "real" Tri-X for small formats is Tri-X 400, coded "TX." Tri-X Professional—TXP—is the rollfilm version of TXT sheet film, ISO 320. TXP and TX are completely different films, with only their name in common. TX 120 will continue to be available. In fact, in response to a question sent by David Goldfarb on APUG, Scott DiSabato, who is Kodak's point person for professional film sales, says that TXP sheet film and TX are still "very strong sellers."
For years, the only Tri-X you could get in large format sheet film sizes was Tri-X Professional, and the only Tri-X you could get in 35mm size was Tri-X 400. However, both film were available in 120 and 200, leading to endless confusion. So, in a way, the current announcement means no more confusion.
Tri-X 400 is the Kodachrome of black-and-white, in my humble opinion, and by far my preference of the two Tri-X's.
(Thanks to Oren)