There can be few people in this world who don't recognise this branding. Even though you can see so little of it. Right now, there's a huge fuss over at iStockphoto.com due to their plan to sell 'stock' logos. It seems that it'll cause the end of the world. Just like stock photos for a $ did. But it seems to me that the best known trademarks are clever typography: CocoCola, Sony, IBM, or a very simple but beautifully executed graphic: Apple, Nike, Shell. As you can't do the former, and the latter is very easy to steal/recreate outside of iStock, it'll be interesting to see how it'll work.