@Andreas Nurbo - This ones for you. http://pressedwords.com/matt-mullenweg-at-greek-blogger-camp-2008/

WordPress version numbers: Mullenweg offered his thoughts on the WordPress version numbering. He admitted that because of the extensive changes introduced in WordPress 2.5, it would have better been called “3.0″ using the typical software version increments. But Mullenweg then complained about applications that have “version infliction inflation,” or excessive version increases, and said that from now on WordPress would do releases on a point-by-point basis, not according to the amount of feature change.

More significantly, he said that WordPress will no longer make releases with major changes. From now on the latest stable WordPress version will be backwards-compatible with the prior release.

So 4.0 really will be just another number, maybe revolutionary or innovative, maybe not. Of course, this is if you're implying that because it will be 4.0, they should absolutely do something innovative to match the version number.