Great to hear! JNW is the main reason I'm putting off installation of Snow Leopard (I'm nearly through a first draft and want to finish it before potentially switching to another program). I'm getting more confident about trying the upgrade.
Users post here
http://www.jerssoftwarehut.com/bbs/viewtopic.php?f=17&t=2101&p=6224&hilit=leopard#p6224that they, too, have successfully used JNW with Snow Leopard, though the 'Recent Files' feature may not keep track of documents before the upgrade. Joachim wisely notes that you'll want to back up your files before an upgrade, a good idea with JNW or anything else.