WebNode cannot start in plugin/jnlp mode without extra permissions. When a dummy application is run through plugin/jnlp, the following exception is thrown:

java.lang.ExceptionInInitializerError
at javafx.scene.web.WebEngine.<init>(Unknown Source)
at javafx.scene.web.WebEngine.<init>(Unknown Source)
at javafx.scene.web.WebView.<init>(Unknown Source)
at dopluginapp.Main.start(Main.java:30)
at com.sun.javafx.applet.FXApplet2$1.run(Unknown Source)
at com.sun.javafx.application.PlatformImpl$3.run(Unknown Source)
at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at com.sun.glass.ui.win.WinApplication.access$100(Unknown Source)
at com.sun.glass.ui.win.WinApplication$2$1.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Caused by: java.security.AccessControlException: access denied (java.lang.RuntimePermission modifyThreadGroup)
at java.security.AccessControlContext.checkPermission(Unknown Source)
at java.security.AccessController.checkPermission(Unknown Source)
at java.lang.SecurityManager.checkPermission(Unknown Source)
at sun.plugin2.applet.SecurityManagerHelper.checkAccessHelper(Unknown Source)
at sun.plugin2.applet.FXAppletSecurityManager.checkAccess(Unknown Source)
at java.lang.ThreadGroup.checkAccess(Unknown Source)
at java.lang.Thread.init(Unknown Source)
at java.lang.Thread.<init>(Unknown Source)
at com.sun.webpane.platform.Disposer.<clinit>(Unknown Source)
... 10 more

Dummy application is attached. Clean and build the application to generate JNLP file and test HTML page for applet.
Please update its build.xml with a proper path to ant-javafx.jar in your local b45 SDK before running the application.