This release really just consists of maintenance for getting jSin fully Firefox-ready in preparation to submit to the Firefox Add-ons Store.
jSin has been approved for release on the Add-ons Store! See the official installation page.
If you're using Firefox, it's recommended to do this instead of installing locally so that you don't have to re-'install' it every time you open the browser. For posterity, the firefox.zip artifact is still available on this release and will continue to be available for download in the future.