I am a big advocate of open source software, but every once in a while commercial software does something that illustrates to me why it will never be completely replaced by open source. I came across
this IEBlog entry at Microsoft recently. For years printing from web browsers has been terrible; you almost never get anything like what the page looks like; elements fall off page borders, content doesn't resize to page width in a sane way, frames aren't rendered correctly if at all, etc.
I hate paper and am completely uninterested in fixing bugs or adding features to projects I am doing volunteer work for that advocate generating more of it. However, I know many people who do print a lot and will definitely enjoy this feature, just none of them are programmers. As an area I'd wager the vast majority of open source developers don't want to touch, I doubt this issue would ever have gotten properly addressed in open source.
Before Firefox, Microsoft had every intention of letting IE stagnate with no additional features or fixes until who knows when. Similarly, Firefox has been stagnating recently with nothing but minor touch-ups since 1.0. Now that Microsoft is adding this feature, I have little doubt it will soon come to Firefox as well, maybe even in time for 2.0.
Now that the competition is heating up again, we should see a new round of improvements out of both pieces of software. Without the different focus brought to software by commercial and open source software alike, both would be worse off.