You can add ArcGIS Server Image Services to the map using ArcGISImageServiceLayer. Image services represent file-based raster datasets or raster collections published with the ArcGIS Server Image extension. You can control the image type, compression type for JPG, image bands, and interpolation type.
You can now define which tile levels of a cached service are exposed in the map. For example, you may want to use ArcGIS Online data for small scales only, then switch to your own cached data at large scales. Or you may want to make a cached service available at large scales only in order to focus the map on a certain geographic area.
You can also force dynamic maps to conform to the scale levels in a tiling scheme. This allows you to show a cached map at small scales, then easily switch to a dynamic map at large scales.
Map service layers have a refresh() method. This is useful if back-end editors are modifying the data and you want to ensure the end user of the application sees the most recent data from the server.
The performance of the graphics layer is improved when adding a large number of graphics to the map.
Dynamic map services can be projected on the fly to match the spatial reference you set for the map. Previously, the spatial reference was defined by the base layer. Now the map can be defined using any spatial reference. Valid only with dynamic map layers.
GeometryService has new methods that allow for creating points in polygons for labeling purposes, and determining spatial relations of geometries. These geometries do not have to come from a map service; they can be geometries returned from a task or a query to a non-ArcGIS Web service.