I like your question ;) It is clear ,taking 奧巴馬 as an example, 奧巴馬",they form it by choosing the characters,that if placed consecutively will give the nearest sound and pronunciation of the original English name.The same goes for 拉丹. Some other transcriptions will depend on choosing those nearly characters with the same sound ,but as well having a connotation referring to something associated with the original word, subject of transcription. For example the French Champs-Elysees is transcribed as 香榭丽舍 ( Xiāngxièlìshè),which means fragrant pavilion and beautiful house all referring to a description of that area and at the same time the word sounds like the original French word. Your question is very interesting is for who is responsible of coining such transcriptions, but I am sure there is an authority in China, who does it . Hope to get an adequate answer from native Chinese :)

Yeah, cherry and gogo are right! And sometimes(most of the time) the English/foreign names translated in Mandarin and translated in Cantonese are different. Obviously it's because Mandarin and Cantonese are so different themselves in pronounciation? This makes the translation pretty interesting too. Take Beckham for example, in Mandarin, it's translated as "贝克汉姆", and in Cantonese, we say "碧咸".( of course, you should pronounce it in Cantonese). This is very interesting in my eyes. :)

Yes! You are right. Basically we chanslate the none by using the nearest sound and pronunciation, then choose the Chinese characters. But many characters are the same pronunciation. We usually follow the Mainstream media, such as CCTV, People's Dialy. What they choose are authority.

Thanks, bubu, for your comment! Ooooops, I picked up "拉丹" from RTHK website, misunderstood it as a Cantonese word!

Just for your information, Bin Laden is translated as 拉登 in Cantonese.