For old releases, please check out our SourceForge Project Filelist Page.
OSCAR 5.1 beta2 has been tagged and the OSCAR 5.1 b2 tarballs for all the supported distros are available here now.
Please give it a try and let us know if you have any problems.
Nightly snapshots are available here.
To build OSCAR from SVN, check SVN instructions.
Package repositories are available. See OSCAR Repositories for including their address in your preferred package management tool.