Coding Horror has an interesting post about The Ugly American Programmer. It is true: English is not only the language of science, it is also the language of programming. Most programming information and documentation is available in English, and the overwhelming majority of programming languages use English keywords. Most important is, as the blog post says:
If everybody blogs and develops in English – our global repository of solutions and blog posts is much bigger and you have better chances of finding an answer to your problem.
This is a reason why I blog in English, although my German is better than my English. There are a lot of good programmers all over the world in Sweden, Finland, Poland, Russia, Spain, etc. Most of them will not understand a word if I post in German. Likewise, I do not understand them if they write in Polish, Russian or Spanish. But if we write in English, we can understand each other. Maybe someone in Estonia has found a solution for a problem you have been working on – but you would not be able to exchange your knowledge without a common language, and if you like it or not, this language is English.