At this time, Linux is really geared towards IT shops that already have Unix installed or have Unix experience. The costs associated with setting up and maintaining a Linux system on a network are more to do with people than hardware/software. However, as the Linux install base continues to grow it's likely that finding people who have real Linux experience is going to get easier.
If you do already have Unix installed, Linux makes an excellent desktop system for managing other similar systems because the cost is negligible. Instead of purchasing an X Window Server for Microsoft Windows, it's generally cheaper to purchase a single copy of Linux and install it. Linux does have a fully featured X Window System with every Linux distribution so GUI support is always available.
Also, Linux systems provide a unique alternative for people who have very special computing needs. Because every Linux distribution contains all of the source code for all parts of the system it becomes very easy to modify that code for specific needs. If you have the skills in house to do this kind of project, Linux is an excellent solution for specific problems. Many businesses are already doing this for POS (Point of Sale) systems.
Linux already has a very solid kernel and so most of the active development focused on usability. This means that within the next year Linux should become much easier to use for people with little or no Unix experience. Interestingly enough however, Red Hat's Bob Young reports in his paper "Sizing the Linux Market, Second Edition" that:
"...It is our experience that the majority of our customers have not used UNIX previously. Last year our registration system survey indicated that 56.2% of Linux users had not previously used UNIX; conversely only 43.8% have had previous experience with UNIX. This year, the numbers showed (and yes we find this hard to believe ourselves) that 81% of those registering their Red Hat Linux products had not used UNIX, while 19% had."
This means that Linux is what people who are interested in Unix are using to learn it and many people are willing to try using Linux even though they have no experience with Unix.
Linux and other open source projects are affecting the computing industry too. As stated in a recent Gartner Group study, Linux is revitalising the Unix industry. It is especially popular in colleges that teach programming and operating system theory. This means students are leaving college knowing how to use Linux systems and will, arguably, use them in their jobs after college.
Examples of very successful open source projects are abundant. Sendmail, which is the most widely used Mail Transfer Agent on the planet is open source. Companies that rely on sendmail include AOL and Compuserve for all their Internet email. Also, the world's most popular Web server, Apache, is open source. Apache is known to run on at least half of the world's public Web servers, including the ZDNet UK site. These two examples demonstrate that businesses and individuals are willing to put faith in open source software. This may be one of the reasons Linux is a rising star.
In conclusion, Linux is becoming a respected and relied upon operating system that offers users a choice as well as being a platform they can all contribute to.