What does it mean when my car inverter's labeling says "Neutral Floating"? Is it safe to use?
Many smaller inverters (and my Honda EU2000 generator) have "floating neutrals".

I don't think "floating" is quite the right term here, as the Neutral will alternately be connected to +170 V or Ground.  What happens is that the inverter has a single high voltage supply (+170 V or so), and connects the Line to that supply on one half-cycle, and Neutral to that supply on the other half-cycle of the AC waveform.  

A load connected between Line and Neutral will see an alternating voltage.  As neither Line or Neutral should be exposed to the user, this technique should not present a hazard, and simplifies the inverter as it does not need to generate a negative high voltage supply.