MySpace released the beta test version of the service without fanfare in a "soft launch" last year and says it spread "virally" to more than 17 million users.
"This is a product with personality," said MySpace co-founder Tom Anderson.
"MySpaceIM was born out of user feedback and we've spent the last year listening to our community and tweaking it to match their needs."
Now a "fully integrated beta service," MySpaceIM can be downloaded online at http://myspace.com/myspaceim, according to the US Internet company.
MySpaceIM is designed to let members of the website easily share videos, pictures and other content from profile pages along with snippets of sound called "zaps" and music.
It is customized for countries including Australia, Japan, France, Germany, Italy, Spain, Britain, Mexico, Canada, the Netherlands, and China.