Is Freon currently contained within commercially available compressed
air cans or other spray can products (e.g., Dust-Off, Lysol)?  If it
still is, which CFCs are prohibited for use by ordinary consumers in
the US?  Or, generally, how is the compressed air (plus propellants)
contained within the aerosol chemically different from regular
atmospheric air (e.g., does it contain ethers, N2O, N2)?

Freon and other CFCs are prohibited by the Montreal convention and
cannot be used in the US.  The propellant in aerosol cans is often a
light hydrocarbon such as propane or a light fluorinated hydrocarbon. 
Nitrogen is also possible.