i think that blizzard has 2 different teams for starcraft and diablo.the diablo team is calling out for people that means that they are working on a project "similar" to them.so i think that they are really working on Diablo not on starcraft
there are two mods. the grapes of wrath and the ressurection. the main difference between diablo 2 LoD is that it is more difficult, your skill tree is changed, u have a lot of new items ,new sets of items and yuor character level grows like two times faster
http://www.joystiq.com/2006/08/24/blizzard-major-project-announcement-in-2007/