The move comes amid continuedover the East Coast Macworld event. Greco announced in October that Macworld Expo was to Boston, ending months of . Apple Computer promptly responded that it would not make the move to Boston and would re-evaluate whether to take part in the final New York show this July.
IDG said the show will go on without Greco.
"While he will be missed, IDG World Expo continues to conduct business as usual with the full support of IDG," the company said in a statement.
An Apple representative said late Wednesday that Greco's departure does not change the company's plans. The representative said Apple has not yet made a decision on the New York show.
Macworld Expo was held in Boston for 12 years before it was moved to the Big Apple in 1998.
In an interview, Greco said he has been talking to Gartner for some time about leaving.
"I've been in discussions with Gartner for a number of months about joining their organization," Greco told CNET News.com.
Greco said he felt comfortable leaving, even though Apple's future participation with Macworld remains unresolved. Greco said before he announced his move, he spoke with key Boston officials including the mayor and the president of the Boston convention bureau.
"I think things are going to resolve themselves with Macworld and Apple," he said. Greco said his current goal is growing Gartner's events business, which currently produces $122 million in annual revenue from its 55 events.
"I'm going to give it my darnest to get to $200 million in a hurry," he added.