I'm having a similar problem but with an ArcGISDynamicMapServiceLayer. If the google maps layer is the base layer, I have the same problem Lizd is having. If I use the ESRI World-Imagery layer as the base layer and hide it behind the google maps layer, it only screws up if the AGDMSLayer is shown before a zoom. After a zoom (whether the AGDMSLayer was visible or not), it has no problem. It seems like it is using the wrong extent to query and display the map. Is this a problem with the gmaps.GoogleMapsLayer? Is this even supported by ESRI? Any insights would be helpful.