The recent announcement by Linus Torvalds that the next release of Linux will be 3.0 has provoked rather furious discussion around the Internets about whether or not the incrementing of the version number is warranted. Linus himself has said that "absolutely nothing" has changed. "It will get released close enough to the 20-year mark, which is excuse enough for me, although honestly, the real reason is just that I can no longer comfortably count as high as 40."
This got me to thinking about the nature of version numbers. Once upon a time (when versions were driven more by engineers and convention, and less by marketing), a version number meant something. Major, minor, revision. A major new release that modified significant portions of the code from the previous release incremented a major version number. Version numbers less than 0 were beta releases.
Linux has been at 2.x since 1996, and at 2.6.x since 2003. Mac OS has been at 10.x since 2001 (even though the current version of OS X is significantly different from the original release in 2001).
Meanwhile, Google Chrome has blasted through major 11 "versions" in three years. Mozilla is planning to release versions 5, 6, and 7 of Firefox this year. You can't tell me that they are going to change major parts of Firefox three times this year. In this case, version numbers are purely being driven by marketing. They need to "catch up" to Chrome and Internet Explorer.
But we live in a different world now. One where, arguably, version numbers are becoming less and less important. The growth of "app stores," I think, is desensitizing your average user to a version number. While apps in the app store still have versions, I couldn't tell you what "version" any of the apps on my iPhone are (other than the OS), and I bet you can't either. Any of the apps I've installed from the Mac App Store I could not tell you the version of them. I just know that, when I see the number on the icon, I know I need to do updates. The updates happen, and I get a new version with whatever new features are there (or, in the case of the Twitter app, whatever features have been removed).
Then there are web apps which are versionless. What version of Gmail do you use? You don't. You use Gmail. Sure, there's probably a revision number or something in the background, but the user has no clue what version they're using. And they don't need to, because there's no action they need to take.
So version are numbered in a wide variety of ways depending on the product and overall seem to be becoming less important as the growth of broadband, "app stores," web apps, and automatic updates make thinking about version numbers less important. So why does it matter if Linus ups Linux to 3.0? Ultimately, it's just a number.