The new project is hosted on OpenCores, but I'm receiving lots of email from people who had difficulties downloading it directly from this website.
If the "Download" link on OpenCores doesn't work, a single-line shell command will do all the work for you:
svn co http://opencores.org/ocsvn/sparc64soc/sparc64soc/trunk
Obviously in order to execute it you will need Subversion installed on your machine and an account created on OpenCores, since it will prompt for username and password.