In 2004, the PSF selected three grant proposals to fund. One of them, "Moving Jython Forward", was only partially completed by Brian Zimmer due to a job change. Some time later, Frank Wierzbicki offered to take over maintenance of the Jython project, but he found that he had under-estimated the amount of work necessary when taking over the proposal from Brian, and he did not make as much progress as he had wanted to.
Martin von Löwis, the Grants Committee chair, has since discussed this project with Frank, and they agreed to cancel the remaining grant funding, as there was likely no chance to achieve the planned goals any time soon.
Jython itself, an implementation of Python written in Java, is still very much worth supporting, and Andrew Kuchling has put support for Jython on his agenda. The PSF will continue to support Jython going forward.