What are the chances OS 11 will be free though? Win 8.1 update is free, so in that respect Microshaft And Frapple are equal this time.
Still shameful that Apple would charge for the equivalent of a Service Pack to their operating system.
There will be no "OS 11" and 10.9 is not "the equivalent of a service pack."
Mac OS X is a marketing name. There was a complete change in the architecture between Mac OS 9 and Mac OS X - It's a completely separate product. Kinda like Windows 95 vs. Windows NT, or Access vs. SQL Server, or whatever.
However, in keeping the "10" at the beginning of the version number, the major version upgrades are now the .1's. So, while MS has released Win2K, Vista, 7, and 8 Apple has released 10.1, 10.2, 10.3... 10.9.
The "service pack" releases are then .0.1 releases, such as 10.8.5.
So, there won't be an "OS 11", the next major version should be 10.10. And it'll be free too, most likely.
Be aware that some of the new iWork apps on OS X are not a continuation of the previous product line. They're built from scratch and are essentially the same as the iOS versions. There are a LOT of annoyed iWork users out there who have discovered the new versions are "dumbed down" and Pages/Numbers lack many features from iWork '09, and there are certain incompatibilities with your existing files.
I am not a Mac OS X user and can't comment directly, but the relevant message boards have seen some heated discussion on the new apps. It's not going over well as far as I can tell.
I certainly am not a big fan of this strategy, but it's not the first time they've done it. Final Cut Pro, for example, was rewritten and lost a ton of features. Now, though, it's back to where it was and then some, with tons of new features, and it runs better and faster.
They did the same thing with iOS 7 - There were some features missing in the first version, but they've already plugged the most annoying holes within a month of release. So, there's certainly a ton of bad reviews right now, but they'll be fine.
I really don't know why they do that, though... Could be pretty annoying if you're one of the people who uses the "unimportant" feature that disappears for a bit!