Open source developers have taken on the task of porting and packaging the official SL viewer for different Linux distributions. They have also contributed heavily to the development of the Windlight add-on, an in-world atmospheric renderer recently integrated into the official viewer. And finally, volunteers have contributed bug reports and patches to the official Linux SL viewer, accelerating its move from alpha to beta status. At the end of 2007, Holmberg says, there were 719 subscribers to the development mailing list, and 64 outsiders had contributed patches.
The article also mentions that they encourage interested developers to visit secondlifegrid.net/programs/open_source.