In which version of Android was encryption of /data made available?

These docs suggest that it has been available (only) since Android 3.0 Honeycomb. By contrast, conversation on discussion boards suggests it was available in 2.3.4 Gingerbread . So, what is the answer to the titular question? *Bonus points if your answer clarifies the following. Are the official docs misleading? Or were those Gingerbread devices instead released **after** Honeycomb, and loaded with some kind of backported encryption feature? Or were those Gingerbread devices instead loaded with some kind of encryption feature added by the device manufacturers, that wasn't part of Android? In short, what gives?*