We have just released a beta of the upcoming 2.2 version. The new version comes with a lot of bugfixes and several great new features. Most notable is the ability to add XMP annotations to linked PDF files. Annoted PDF files carry all relevant citation information, for easy sharing between JabRef users. Other new features include new advanced HTML export filters, better search, better drag-and-drop support for PS/PDF files, linking to PS/PDF files placed relative to the bib file, and quick letter seek in the entry table.
We'd like to root out the bugs before making the final 2.2 release, so please report anything that doesn't work right! (Unless you're one of our translators, please don't report warnings about missing transkations)