The Financial Times has comprehensive article on the global use of the English language. I recommend all localization-industry chanters of “EJAL” (English is Just Another Language) read it immediately.
The article tells us that:
The reason millions are learning it is simple: it is the language of international business and therefore the key to prosperity. It is not just that Microsoft, Google and Vodafone conduct their business in English; it is the language in which Chinese speak to Brazilians and Germans to Indonesians.
What’s interesting is that the linguistic dynamics between the notion of native and non-native speakers are clearly changing too.