It was not more than three years ago, that Linux was just a hackers operating system. Now IBM, Intel, Apple, Oracle, and just about every big player on the field (except Microsoft, for obvious reasons) are using Linux in their low end computer servers, or porting their software applications to Linux. Additionally, millions of dollars have been poured into the software development for Linux applications.
For example, the Apache web server is in use by over 70% of the Internet communities. Everyone from the local Internet service providers (ISP's) to (ironically enough) Microsoft owned, Hotmail.Com. Other software vendors like Corel (whom provide the Corel Office Suite, a Canadian based company) is pouring money into the open source project WINE. WINE is an application programming interface (API.) An API is a set of basic functions that do very menial tasks at the low level in the computer system. In this way, the programmer can concentrate on features in his program, and leave the low level programming to this library of functions which he may call upon at will.
This particular API (the WINE API) is a windows program emulator. It allows people whom have written programs to exclusively run on Windows, with little effort, port the programs to Linux and compile. Corel poured money into the project so that it could port it's Office suite from Microsoft Windows to Linux without rewriting the Windows version of the office suite.