Ubiquiti sells some devices that are 24V passive PoE. These devices include their UISP products (such as devices like the AirMax). Passive injectors are dangerous because they always supply 24V to the port; this could damage a non-24V PoE device.

There's also the 802.3a* standards family, such as the 802.3at (what Ubiquiti calls PoE+). Each of the standards (e.g. 802.3at, 802.3af, etc.) support different amounts of current, but they're all 48V active adapters. Active PoE is safer because the device "requests" the power it wants; the switch does not always supply 48V power over the port, so devices that don't require PoE won't be receiving power.

Ubiquiti sells a few switches that support both 24V passive PoE and 48V active PoE. You can change this in the switch's web interface, through the port settings. You may also want to consider just using a 24V passive injector, especially if your switch cannot be configured to supply 24V power.

The rest of Ubiquiti's gear does use IEEE 802.x.