Development versions of PRISM include recent improvements, extensions and bug fixes not yet available in the main public release. These are usually either recent snapshots from the PRISM developers' Subversion repository or beta versions of upcoming releases.
They are usually available just as source code and as a Windows installer and, like the main PRISM releases, are distributed under the GPL. Please feel free to ask questions in the forum. As usual, your feedback, good or bad, is very much appreciated.