My impression is that most people don't know what steam is, or rather they use the term to describe water droplets in suspension. Steam is water in its invisible, gaseous state, but without the presence of liquid water (in which case it should be called water vapour rather than steam).
In fact a boiling kettle illustrates it all rather well. Immediately at the spout there is invisible steam emerging, but as it mixes with cooler air it begins condensing, becoming visible as liquid water droplets. As this mist rises and mixes more with cooler air it will evaporate again and become invisible water vapour.
I must admit the terminology is confusing, so I'm not particularly surprised that even the Energy Saving Trust got it wrong. Perhaps we should just use the terms cloud or mist to describe water droplets in suspension in air.
