I have tried openfire_2008-11-17 nightly, but it has no affect on my problem with uninstalling the plugins. This happens only on my Windows box. Linux box is working fine with that. Uninstall takes a minute or so. Then it will show that plugin was uninstalled, but it still lists that plugin on the Plugins page as installed. After another few minutes it will finally dissapear. But he folder of such plugin in /openfire/plugins/ will stay until next openfire start. If i try to uninstall another plugin, then suddenly first uninstalled plugin appears on the list again.
Testing of the fix is pending. Code is in SVN now.