according to Wikipedia:
In principle, in subsequent releases, the major number is increased when there are significant jumps in functionality, the minor number is incremented when only minor features or significant fixes have been added, and the revision number is incremented when minor bugs are fixed.
again, according to Wikipedia:
KDE 4.0 was released on January 11, 2008. Despite being a stable release, it is intended for early adopters. Users wanting a stable, "feature complete" desktop may wish to continue using KDE 3.5 for now.
Kubuntu will be released this month with KDE 4.0, Mandriva was released with KDE 4.0.2, and SUSE will be released just few days before KDE 4.1 will arrive, with latest KDE 4.0.x on board.
I am not against releasing. I am just afraid of possible low quality of KDE 4.1 from update centers...