At the moment there is nothing to download, because the SourceForge staff have to import the repository.
When the first release comes out, you can download a source tarball, a windows version, a linux version and maybe a mac version.
Thanks to the SourceForge staff for importing the iridescence repository in only one buisness day. :-)
cvs -d:pserver:anonymous@cvs.sourceforge.net:/cvsroot/iridescence login
cvs -z3 -d:pserver:anonymous@cvs.sourceforge.net:/cvsroot/iridescence co iridescence
cvs -d:pserver:anonymous@cvs.sourceforge.net:/cvsroot/iridescence logout
If you simply want to view the source code, go to the web-based source code repository.