Arguably, programmers should program only in English, using English language toolsets. I've worked in several European countries, and that's what all the teams I've worked with did. Working in English has lots of advantages - you can post coding questions easily, you can google for error messages and get better results, and you can hire people from different countries. If you are not programming in English and/or not using English language tools, I have to ask - why?
Note this does not mean that your applications textual resources must be in English - obviously they should be in the language of your end-users.