Honestly, I thought that the "logo cloud machine" or "floating logos" from Skywriting flogo.net would be responsible for spewing Nike swooshes or similar logotastic nothings all over the place by now - but it seems the first person to make clouds in a big way is Stuart Semple who uses his machine to spread smiley faces all over large cities.
Happy Clouds Demo
Here he is on the BBC Show "Blue Peter" demonstrating his happy clouds, adding a dash of blue to it as well. The clouds are smiley faces that floated around London that day.
Stuart has also done an installation where he released 2057 pink smiley faced clouds which floated from the Tate Modern toward the financial district in London.
Happy Clouds - Stuart Semple - London
Artist's website: stuartsemple.com
(as for advertising being everywhere, it is remember the possibilities of making logos in water now)