And a growing percentage of that knowledge can and should be available in your native language.
That may be true, but still, being fluent in English is incredibly useful whenever using the internet for, well, anything. For example, I’m a native speaker of German, so it’s natural for me to search in the German Wikipedia for anything I want to know. But more often than not, the English version of an article is much more up-to-date, informative and comprehensive than any other version, so I end up reading the English version instead of the German version. The same goes true for most UNIX/Linux man pages, the translated versions often lack critical information, so reading the English original is sometimes simply mandatory.
The same is true when searching for any technical problems on the net: When using English search terms, the count and quality of search results is nearly every time much higher.
In university (I’m a master of science in CS) they always told us that being relatively fluent in English is a very important skill in the software industry throughout the whole world, and none of us students questioned that. Many great books that were recommended to us are only available in English, or the translated versions contain just too many translation errors to be enlightening. We also could choose whether we wanted to write our bachelors/masters/diploma thesis in German or in English, both being normal choices.
I tried to use localized software for development in the past, but most of the time, it was a painful experience (barely understandable to non-understandable compiler error msgs, etc.), so I’ve given it up completely, and use the English (=original) version of every software (IDE/Webbrowser/OS/etc.) whenever I’ve got the chance. We also have the guideline at my current job that our sourcecode (including comments and SVN commit messages) should be 100% English whenever possible, because many of us (including me) think that it’s just more professional and makes the code more valuable, because most skilled software developers on earth know at least enough English to understand the code’s comments.
Also, there are more than enough great blogs that are only available in English, so I would recommend learning English to anyone that has any kind of interest in the computer sciences.
But I believe the rules are different for programmers. So much so that I’m going to ask the unthinkable: shouldn’t every software developer understand English?
Well, if you don’t, that can severely harm your career, at least in Germany. Don’t know about other countries, but as I said, they told us that it’s basically the same everywhere. Maybe except for France, the french are extremely in love with their language, and try everything to protect and save it. So possibly, the rules are different there.
In my opinion there is no reason to translate developer tools and documentation.
I second that completely, more often than not, the original version is incredibly much more understandable, up-to-date, concise and basically the only sane choice. So there are many developers (probably the majority) that just plainly ignore the translated version and use the original. I recommend this to every colleague, and most agree.
The only exception are technologies that are only relevant in Germany, for example, there’s a technology called HBCI that is being supported by many German banks for home banking, but only by German banks. So the specification and most of the documentation are only available in German. Also, another technology named ISDN is quite popular in Germany, but not very popular in most other countries. So much software, tools, documentation etc. are only available in German, too. But this are the only two exceptions that I know of.