No, not yet anyway. It would be nice.
But you can sort your objects into different folders in the Objects folder of your project window. Just right-click the Objects folder and select "Add object folder." You can rename them and drag your objects into them.
This also has the added benefit of putting your objects into sections when you go to the Event Sheet editor, so you don't have to hunt through a hundred little icons to find the one you want.
If the Object panel was a copy of the folder tree in the project tab that would be useful. With more sorting options, of course.