Updates have always been free.
Upgrades are paid for.
Part of the upgrades thing is that of course, as a subscriber, you will always be current on whatever version is out there (CS6, CS7, CS8, etc). But another thing is that as new features are developed, Creative Cloud members will see those features deployed to their software as soon as they are ready, whereas perpetual license members likely won't see some features until CS7 is released 2 years from now, and even then, only if they purchase the upgrade. That's how that works.
For updates like 6.01 or 6.1.2 or whatever, those are typically small updates (not upgrades) and are no additional cost. In the past, when there has been a "X.5" version, that is when Adobe has designated it as a purchase upgrade.