Apparently Microsoft provided support for this in an unofficial 'Futures' release but they have yet to release this support officially.
Does anyone know if this will be supported in ASP.NET 4.0?
More info here
http://forums.asp.net/p/1380982/2930653.aspx and http://waitink.blogspot.com/2008/06/ajax-web-parts-part-1-drag-and-drop.html
Thanks.