As of late last night, you can now download (no SVN required) a tarball of a fully-operational Solar system with the 1.0.0alpha2 code in place: http://svn.solarphp.com/system/download/solar-system-1.0.0alpha2.tgz.

The three-step install instructions are also included - check out the download page for a quickstart guide on using this new code.