I'm trying out LilypondTool, the version which is downloaded within jEdit is 2.12, I've downloaded 2.14.20111117 and copied the jars to the .jedit jars folder, and copied lilypond.xml to the modes folder (replacing the orginal, which on windows is in the Program Files jEdit folder, not in the user .jEdit folder where the jars are.
jEdit Plugin Manager now says I have 2.14.20111117 running, however..
1) The interface looks no different to before that I notice, and notably different to the flash demos on your site.
2) I get no automatic preview, although that is ticked in the options, if I change something in the source, the pdf doesn't change, even if I save.
3) There is no LilyjHelp.jar file in the download, rather a zip file containing pngs and xml files and no instructions what to do with it.