Just four months after becoming the official “Co-President” of MySpace.com, Jason Hirschhorn is leaving the company.

Mr. Hirschhorn’s departure is just the latest blow for the social networking Web site, which the News Corporation bought for a staggering $580 million five years ago.

MySpace has struggled to retain audience and relevance in the shadow of the much more popular Facebook. It averaged about 111 million visitors worldwide in April, while Facebook averaged 519 million, according to ComScore….TechCrunch reported on this last week.