Index: src/org/openstreetmap/josm/gui/actionsupport/AlignImageryPanel.java
===================================================================
--- src/org/openstreetmap/josm/gui/actionsupport/AlignImageryPanel.java	(revision 0)
+++ src/org/openstreetmap/josm/gui/actionsupport/AlignImageryPanel.java	(working copy)
@@ -0,0 +1,83 @@
+package org.openstreetmap.josm.gui.actionsupport;
+
+
+import java.awt.BorderLayout;
+import java.awt.Color;
+import java.awt.Font;
+import java.awt.event.ActionEvent;
+import java.awt.event.ActionListener;
+import javax.swing.BoxLayout;
+import javax.swing.JButton;
+import javax.swing.JLabel;
+import javax.swing.JPanel;
+import javax.swing.Box;
+import javax.swing.JSplitPane;
+import javax.swing.border.CompoundBorder;
+import javax.swing.border.EmptyBorder;
+import javax.swing.border.EtchedBorder;
+
+import org.openstreetmap.josm.Main;
+import static org.openstreetmap.josm.tools.I18n.tr;
+import org.openstreetmap.josm.tools.ImageProvider;
+import org.openstreetmap.josm.tools.UrlLabel;
+
+
+/**
+ * The panel to nag a user ONCE that he/she has to align imagery.
+ * 
+ * @author zverik
+ */
+public class AlignImageryPanel extends JPanel {
+    private static final String PREF = "imagery.offsetnagging";
+
+    public AlignImageryPanel() {
+        super();
+        
+        Font font = getFont().deriveFont(Font.PLAIN, 14.0f);
+        JLabel nagLabel = new JLabel(tr("Aerial imagery might be misaligned. Please check its offset using GPS tracks!"));
+//        JLabel nagLabel = new JLabel(tr("Снимки могут быть смещены. Не забудьте проверить привязку снимков по GPS-трекам!"));
+        UrlLabel detailsList = new UrlLabel(tr("http://wiki.openstreetmap.org/wiki/Using_Imagery"), tr("Details..."));
+        nagLabel.setFont(font);
+        detailsList.setFont(font);
+        
+//        JButton closeButton = new JButton("X");
+        JButton closeButton = new JButton(ImageProvider.get("misc", "black_x"));
+        closeButton.setContentAreaFilled(false);
+        closeButton.setRolloverEnabled(true);
+        closeButton.setBorderPainted(false);
+        closeButton.setToolTipText(tr("Hide this message and never show it again"));
+        closeButton.addActionListener(new ActionListener() {
+            @Override
+            public void actionPerformed( ActionEvent e ) {
+                setVisible(false);
+                getParent().remove(AlignImageryPanel.this);
+            }
+        });
+        
+        BoxLayout box = new BoxLayout(this, BoxLayout.X_AXIS);
+        setLayout(box);
+        add(nagLabel);
+        add(Box.createHorizontalStrut(12));
+        add(detailsList);
+        add(Box.createHorizontalGlue());
+        add(closeButton);
+//        setBorder(new EmptyBorder(12, 12, 12, 12));
+        setBorder(new CompoundBorder(new EtchedBorder(EtchedBorder.LOWERED), new EmptyBorder(12, 12, 12, 12)));
+        setBackground(new Color(224, 236, 249));
+    }
+    
+    public static void addNagPanel() {
+        if( Main.map != null && !Main.pref.getBoolean("expert") && Main.pref.getBoolean(PREF, true) ) {
+            if( Main.map.mapView != null && Main.map.mapView.getParent() instanceof JSplitPane ) {
+                // This is really a hack. If you don't like it, use the line in "else" block
+                JPanel p = new JPanel(new BorderLayout());
+                ((JSplitPane)Main.map.mapView.getParent()).setLeftComponent(p);
+                p.add(Main.map.mapView, BorderLayout.CENTER);
+                p.add(new AlignImageryPanel(), BorderLayout.NORTH);
+            } else
+                Main.map.add(new AlignImageryPanel(), BorderLayout.NORTH);
+            Main.pref.put(PREF, false);
+        }
+    }
+    
+}
Index: src/org/openstreetmap/josm/actions/AddImageryLayerAction.java
===================================================================
--- src/org/openstreetmap/josm/actions/AddImageryLayerAction.java	(revision 5050)
+++ src/org/openstreetmap/josm/actions/AddImageryLayerAction.java	(working copy)
@@ -10,6 +10,7 @@
 import org.openstreetmap.josm.Main;
 import org.openstreetmap.josm.data.imagery.ImageryInfo;
 import org.openstreetmap.josm.data.imagery.ImageryInfo.ImageryType;
+import org.openstreetmap.josm.gui.actionsupport.AlignImageryPanel;
 import org.openstreetmap.josm.gui.layer.ImageryLayer;
 import org.openstreetmap.josm.tools.ImageProvider;
 
@@ -43,6 +44,7 @@
         if (!isEnabled()) return;
         try {
             Main.main.addLayer(ImageryLayer.create(info));
+            AlignImageryPanel.addNagPanel();
         } catch (IllegalArgumentException ex) {
             if (ex.getMessage() == null || ex.getMessage().isEmpty()) {
                 throw ex;