The extremely simple circuit produces many harmonics. Some harmonics are in the AM broadcast band and other harmonics cause interference with many communications frequencies (police, fire department, ambulance, aircraft, TV etc) then you will be in BIG trouble.
The datasheet for a 555 shows that C2 can be as low as 1uF. 1000uF is not needed.
I see what you think ramesh, the transmitter would probably produce a better signal of fm, I think they are relying on a sort of pulse width method to transmit on am, its very crude but works on am too, I have a grip dipper that makes an audible tone using the same method.
Anyone interested in radio will slate this as it produces square waves and transmits on several frequencies.