Remember that foreshadowing is defined as any hints or clues that the author places earlier on in the novel that act as predictions or indications of what will happen later on. If we think about this definition, there are certainly lots of examples of foreshadowing in this great book - authors use foreshadowing to create suspense.
One of the most important examples comes in Chapter 2, entitled "The Vanishing Glass." In this chapter, we see an example of Harry's latent magical ability as he makes the pane of glass separating Dudley and the boa constrictor vanish so that Dudley falls in:
Harry sat up and gasped; the glass front of the boa constrictor's tank had vanished. The great snake was uncoiling itself rapidly, slithering out on to the floor - people throughout the reptile house screamed and started running for the exits.
This event of course foreshadows Harry's identity as the son of a witch and a wizard and as somebody chosen to go and study at Hogwarts to become a wizard himself.