On behalf of the Jython development team, I'm pleased to announce that Jython 2.5a3 is available for download at http://downloads.sourceforge.net/jython/jython_installer-2.5a3.jar. See the installation instructions here: http://jython.org/Project/installation.html
Jython 2.5 Alpha3 fixes a bug that caused installation problems for many Windows users, so Oti Humbel and Leo Soto came to the rescue with an assist by Geoffrey French. Oti also fixed standalone mode while he was there. Yay!
As before, this is an alpha release so be careful.