Awesome timing for this, yesterday I was imagining how awesome it would be if Obsidian developed a Mass Effect title and Bioware did a Fallout. Notice I said imagining, because the current world we all live in would not allow anything awesome to come from this idea.
What, Mass Effect would be buggy and stilted, but have vast open environments which to explore (much like the first, I guess!) And Fallout would be traversed through a dot map, where you get to see 3 acres of wasteland, before magically being transported to another 3 acres. Woohoo!