OS X Lion will replace the current OS X version which is nicknamed Snow Leopard.
“I wanted to let you know that I’ve requested that you be invited to the prerelease seed of Mac OS X Lion, and you should receive an invitation soon,” said a letter sent by Apple to the security researchers. “As you have reported Mac OS X security issues in the past, I thought that you might be interested in taking a look at this. It contains several improvements in the area of security countermeasures.”
All security researchers also have an NDA to sign when they would like to comment on the new operating system. But is sure is a good move from Apple to have their new OS examined by a part of the security community.