Several years ago, at the last Linux Desktop Summit, I said that my measure for success of "Linux on the desktop" was to be able to do 100% of my desktop computing on a machine that ran only open source software. Although I have advanced degrees in computer science and was (am) willing to do command-line customizations and installations, I took the perspective of the average non-professional user seeking a home desktop solution that is roughly comparable to MacOS X and various Windows implementations.
At the time, I estimated that we were around the 50% mark toward that goal (lots of missing device drivers, buggy OpenOffice, no high-quality equivalent tools for photo editing, page layout, video editing, and much more). In short, anyone using a Linux desktop would need to have another machine to accomplish these other tasks.
In recent weeks, I have installed SLED 11, openSuse 11.1, Fedora 10, and Ubuntu 9.04 on several netbooks, notebooks, and boxes. My goal (once again) was to make one of these systems my everyday workhorse machine, one that I could recommend to friends and family for all of their computing tasks. While the situation is much improved from three years ago, we are still quite a way from reaching that elusive 100% goal. For myself and my family, I would guess that we are in the 80's, but gamers would give a much lower score.
Installation and setup is vastly improved. The desktop layouts, particularly GNOME, are reasonably familiar to users of other platforms. Individual applications, notably OpenOffice and Firefox, have come a long way. The usability of system update mechanisms ranges from the smooth (Ubuntu) to the challenging (SuSE). (Development tools are outstanding, but that isn't the issue here.)
However, I had to install restricted drivers to make wireless work, had to install commercially licensed Flash to be able to view many websites, and still found myself without programs for video editing, page layout, and photo editing that compared well with their commercial counterparts (e.g., Scribus vs. MS Publisher or Pages). Watching commercial DVDs occasionally required the use of terminal commands to download and install software, not to mention the associated legal issues. Webcams and microphones were unreliable at best, making it impossible to do video chat or broadcasting (e.g. uStream) with web-based applications.
So I renew the challenge to make it possible for average computer users to do 100% of their work using open source software. That means moving development efforts up from the operating system and infrastructure level to concentrate on creating high quality, easily used applications. That also rules out using WINE or VirtualBox to run proprietary apps.
Let's create personas and scenarios for different types of users, identify their needs, and build the needed applications and drivers. Let's also continue to push device makers to supply Linux drivers. Let's find a workable solution for Flash and SWF-based web content. (Gnash isn't quite there.) In that way, we can make some progress toward that magic 100% number that would allow people to do all of their computing on a Linux desktop.