Why does the Roman Catholic church consider beatification of the pope? If the pope is infallible, than what significance does beatifying and canonising him have?  They did both to John Paul II, but it seems odd that the church wants to make him a saint, unless I am misunderstanding the concept of saints.
First, Catholic teaching is not that the Pope is infallible in everything he says and does, but rather infallible only when specifically exercising the authority of his office to pronounce doctrine.

Second, a Saint in the sense meant by the Catholic church is one whose life, witness and actions have been examined in depth and at length by church leadership and has been found to be significantly exemplary of the Christian ideal.  They are recognized by the Catholic church as examples to emulate, and are made "official", so to speak, so that there is no confusion among believers as to what constitutes a great example.

Also, as Patrick pointed out in the comments, other conditions and prerequisites apply; among them is the requirement that at least two miracles be directly attributable to the individual under consideration.

Therefore, a Pope is not automatically a Saint (with a capital 'S' since all believers are saints in the general sense); in fact, historically, many of them were decidedly unchristian in their actions and some downright wicked.  Some very reputable Catholics have said that the preservation of the doctrine of the Catholic church in spite of some of her Popes is remarkable, if not nothing short of miraculous.