As a long-time Linux user myself (I also run Vista and Mac OS, depending on which machine I have going for the day), I can tell you that the consumer prospects have always been minimal. Each distro seems to have you follow a completely different set of rules for installing apps and finding what you need, and something as simple and archaic as copying a file can be mind-numbingly complex for new users. Just try inserting a WWAN USB card or configuring Wi-Fi after a fresh install: not for the faint of heart.
Yet, the fact remains: as the OS you use becomes less and less important, and as Web 2.0 sites, online apps, and cloud computing (especially the emerging idea of "data-as-a-service) become more and more prevalent, the Linux OS could really capture an audience. I know, for me, I can switch to a Linux laptop and find all of my documents, check my e-mail, find contacts and to-do lists, and stay just as productive as I am with a Mac or PC laptop. There is no discernable difference for me, but then my day consists mostly of research and writing, not necessarily as much advanced photo editing or number crunching in a spreadsheet - unless I have an article on those topics. Even then, there are usually perfectly stable and highly functional open source equivalents to the most common desktop apps. Each year brings another new crop of more powerful online tools, more reliable online storage, social networking that is less of a buzzword and more of a critical part of our business day, and more streamlined UI.Where is this all leading? For the average consumer, they will likely start "sticking" to the Web so much that they stop caring whether they see the Windows logo when they boot-up. And I think Linux will be waiting in the wings, ready to take over - just as it has in data centers - and pummel the competition. We could all one day be living in a Linux world where Mac and Windows are trite archaic old world operating systems for people who still don't get FaceBook and Twitter.