From Jahwiki

Currently there are no stable releases available. Currently only early test builds are available. Please watch this page for updates in the future.

[edit] Windows

http://rapidshare.com/files/86861138/jahplayer-0.3.0-installer.exe.htm

[edit] MacOS

http://rapidshare.com/files/86861138/jahplayer-0.3.0-installer.exe.htm

[edit] Linux

Not packaged yet

Please report all occurring bugs to http://jahshaka.org/forum/jahplayer-0-3-0-build-t1688.html?t=1688&highlight=jahplayer or directly to trac.

Thanks for your support.