Schneider,
A great documentary to watch about Membranes ('Branes) and all things String and M Theory is "The Elegant Universe" It's a Nova production so it should be available for viewing or download from their site or try PBS.org
It explains a lot in terms non-physicists like us can...
I read (or heard or saw) somewhere long ago that if you traveled as far as you could go in the Universe you'd return to the exact same point at which you started. If our U is indeed a 'brane, and the previous statement is true, doesn't that whole circuit of travel ending up back at "point A"...