I found this article and it fits nicely into my teaching of Superpowers at the moment (Edexcel A2); having moved from a uni-polar world (British Empire), to a bi-polar one (Cold War) and then back to a uni-polar world again with the U.S. as the world's number one hegemonic superpower. The question is, for how much longer will the U.S be number 1; especially considering how interconnected the world is through globalisation and the rise of emerging superpowers like China and India.
http://web.worldbank.org/WBSITE/EXTERNAL/NEWS/0,,contentMDK:22920320~pagePK:64257043~piPK:437376~theSitePK:4607,00.html
http://web.worldbank.org/WBSITE/EXTERNAL/NEWS/0,,contentMDK:22920320~pagePK:64257043~piPK:437376~theSitePK:4607,00.html