Today I added the BitmapConverter.cs which will support returning a Bitmap directly from Ajax.NET Professional . Attached to the Google groups thread  you will see what is working today (the Bitmap example is the method Test27). Of course, I didn't add all data types... ;)
If you will return a Bitmap you can access the Bitmaps source location or create an Image object from it:
What do you think? Write your feedback in the Google group ...