I don't know if a gas powered leaf blower could create enough thrust to make a plane fly, but since the FT crew made a turkey and cinder block fly this should be easy! Anything goes for design, as long as it gets thrust only from a leaf blower.
That would be awesome. I know people have used leaf blowers as turbos on their car and got a noticeable gain in power. Not sure what the actually thrust of a turbo is, but should be enough to fly the right design.
In the same vein, I wonder if you could take the blower from an electric unit and power it with a BLDC motor. My guess is that the motor and fan share a common shaft, so the real challenge would be mating the two together.