To gather feedback from the community at large, Sun has been posting source code and binaries for Mustang regularly. This has not always sat well with engineers developing the release.

"Putting raw source code up was really jarring to them," said Jean Elliott, director of developer marketing at Sun. "They didn't want to see something [published] that was in the process [of being developed], and we've overcome that."

Sun recently postponed the general release of Mustang from this summer to the fall, citing the need for more time after changes were made to Mustang's classloader. Additionally, Sun has launched a contest for developers to find regression issues in Mustang.