We've got heads on sticks
You've got ventriloquists
This refers to revolutionaries (executing the ruling classes and displaying their heads) and political masters (using media-friendly puppets to convince us they have our best interests at heart.
One popular theory over this song is that it tells the tale of the first human clone — i.e. Kid A.
If so, heads on sticks and ventriloquists would refer to those that raise him as a scientific experiment.
To help improve the meaning of these lyrics, visit "Kid A" by Radiohead Lyrics and leave a comment on the lyrics box