Steve,
I think the simplest solution is having a rest service that returns your points based on the user session id. Once you get the points, create a graphic layer and add these point to the layer, so they will always be at the top of the map with a symbol you defined.
The only thing to look after is the spatial reference, if the points are the same as the base layer, no transform is needed, if not it could be that you will need a transform using the project method of the geometry service of your ArcGis server.
Johnny