CBR has posted early X title comic solicitations for September 2009, including two Deadpool books. The solicitations reveal Deadpool #15 and Deadpool: Merc With a Mouth #3. The full September solicitations haven't been released yet, so Deadpool may also appear in other books. Thanks to Ben for the tip. [SOURCE]
UPDATE:
Newsarma's early Marvel solicitations also revealed that Deadpool will appear in the the Shang-Chi: Master of Kung-fu one shot, featuring "It’s DEADPOOL versus SHANG-CHI, the peerless Master of Kung-Fu, in a KUNG-FU MOTORCYCLE RACE!" [SOURCE]UPDATE #2:
Marvel.com has also released early Hulk solicitations, and it has been revealed that Deadpool is also in Hulk #15. [SOURCE]