Apparently, there is some contract hold-up and he's not scheduled to compete at this point. MLE president Richard Shea issued the statement below.
"Takeru Kobayashi is currently not scheduled to compete in the 2010 Nathan's Famous July Fourth Hot Dog Eating Contest. In recent weeks, Major League Eating has sought to arrive at an agreement with Kobayashi, but contract negotiations have reached an impasse. MLE remains hopeful that Kobayashi, who won the contest from 2001-2006, will decide to compete this July 4th in Coney Island, when Joey Chestnut will seek his fourth consecutive title."
According to sources, Kobayashi is considering signing with the Miami Heat next season in order to dethrone Joey Chestnut.