One great thing we see with Linux is that it's used for servers quite frequently, it's probably one of the strongest points about it. A strong and stable server platform which many companies rely on to run many parts of their infrastructure for an organisation.
A common situation we'll see are MMORPGs, games with thousands of players mostly with Windows clients connecting to servers powered by Linux. Occasionally you'll see people trying to run their game client under WINE, but it isn't quite the same as running a native game. These companies use Linux to run their gaming servers, web servers and possibly many other parts of their infrastructure, but when it comes to building a Linux client for their game they'll rarely consider it or even dismiss it without even considering the feasibility of it.
I don't think anyone expects companies who use Linux to start contributing hundreds of lines of source code back to various projects, but it would be nice if they considered a Linux client of their product where it's viable as a way of saying thank you. They're getting the benefits of many hours of effort being placed into a freely available operating system, but they're not helping this operating system by refusing to release their product for it.
In an ideal world we'd see multi platform clients, maybe we'll see more if it one day.