I really like the whole ethos behind FOSS.
My background is with Big Multinationals, which I've left behind to work for a 'Non-Profit small enterprise. We were MS through and through and I was responsible for Technology from robotics & automation systems through to Enterprise IT. MS do some reasonable OS's - XP, some rubbish - Vista and some good - 7. They also do good training. Generally Linux distributions seem to be all pretty reasonable to good. However, training is a BIG issue. I was funded to do the RedHat official 2 week, client & Server level courses 3 years ago. To say they were rubbish, makes Vista look superb. Here lies a major flaw. Like many IT pros, just trying to keep up is difficult, let alone picking up new OSs, although I did actually start with Unix. As many PCs come with a well known, understood and supported OS, people do not have an incentive to move or try anything else, especially if the risk are higher, due to lack of support. Take 2 tech disk cloning products, Norton Ghost and Clonezilla. Ghost just works, has a simple interface yet costs. Clonezilla, the FOSS solution, has a complex GUI, complex features, which are poorly described and sometimes needs tweaking. FOSS is great, but solving issues with it is like expecting users to play with windows registry. Why, when many users don't understand the difference between Windows Explorer and Internet Explorer! People like to feel safe and I don't believe that us IT pros are able help enough people feel safe with Linux yet, but it could come. People need to feel reassured. Anyway, I do take your point, and will be using FOSS apps on top of Windows XP for the YWAM base I'm visiting later on this year.

A few years ago finding an OS for Linux would be hard but recently mainstream OS's have come up that are supported well. Dell now offers Ubuntu as a pre-installed OS which means that it's well enough supported for them to stamp Dell on it. System76 offers Ubuntu as their only OS. Linux is just getting easier to use on the client side.

If you're talking on the IT side then we shouldn't be waiting for mainstream stuff since most of what we can do should be done in the command-line. Not in the GUI.

I do agree that people need to feel safe but, in my experience, all it takes is someone with a little authority on a Linux OS to support it enough to make them feel safe. It's just about practical training.

I was really excited when I found your post mate! I am in a pioneering situation and as you can tell from my username also a FOSS and Linux buff, currently running Ubuntu on my PC and hoping that when we have the need for campus computers to use almost all Linux and Foss, with exception to those who are partial to their Mac's. Linux certainly has come a long way in the area of user compatibility when it comes to the GUI.
anyways I was quite encouraged!

I know, I come a bit late to the table... Anyway.
Personally I run all Desktops, Laptops and Servers with Linux. At least for me, it works brilliant.

However, I must admit that I have Windows powered phone (shame on my ;) I know). But that is a bit dated, it is pre iPhone/Android era (yes, it is old, but still working well). Sadly, available alternatives, e.g. with Symbian, weren't really an alternative here at that time. So, even though I didn't really want a Windows Phone, it was the best possible tool for the job.

Also, my wife is (still) running WinXP as this works better for her at the moment. The Base runs all Windows, except some RDP Clients, and she's using her computer to work there. The things I do don't depend on Windows, so I'm free to run (on my personal laptop) what ever I want, while not being restricted in any way.

I don't see any real blocking points for Linux nor for FOSS in general. As always, use the tool that suits your needs. If that is either Linux, OSX, or Windows (or something even more uncommon) then so be it. Some might want/need to run different systems.
If you need a proprietary application for $task then so be it. I have no problem with that.

What I do have a problem with is when people "absolutely certainly desperately need" an application because of $function while basically only using 5% of the capabilities of said application. But are deaf to the fact that there might be multiple FOSS alternatives that can do just the same, though might have to click at a different menu to achieve the same.
Please forgive me if that sounds a bit hard and direct. But it is simply beyond me that sometimes, too many times actually, $200 or much more is wasted on an application that isn't really used anywhere near its capability.