wikipedia is not the last word on any subject. i maintain that hinduism is not a polytheistic religion.
even north indians worship a multitude of gods and goddesses. not many people take the trouble to read the original texts. The foremost representatives of orthodox hinduism like Adi Sankar, Madhava, Ramanuja, and others all agree to there being one god. when budhist and jain atheists (like the jain philosopher Gunaratna) refute the hindu notion of God they are refuting a monotheistic definition of God. the upanisads explicitly state that there is only one god.
The sublime philosophy of the Hindus declares that God is one. God is the ultimate divine Reality. The ancient sages of Hinduism clearly stated, "The Reality is One, the wise ones refer to It variously (by various terms)." We have the significant announcement, "Ekam sat, vipraha bahudha vadanti." This truth they declared when they spiritually discovered It through their direct personal experiences granted by Divine Grace. Therefore, a real follower of true Hinduism knows and therefore firmly believes that the Divine Reality or God is one and non-dual. Even though Hinduism is mistakenly regarded by many as a religion having many gods namely, polytheism, yet truly speaking Hinduism is a monotheistic religion. It is a religion that long long ago, before any other religion had appeared in this world, had discovered that there is only ONE GOD. Later on our spiritual ancestors, the sages of God-experience and illumined vision, attained also the knowledge that the various religions of man are like so many different ways and paths that finally lead to this ONE God who is behind and beyond all religions including Hinduism. The Supreme Almighty Being (God) does not belong to any religion. Because, God existed even before this universe and mankind were created, even before any religions have come into existence. All religions belong to God. Because, He is the source as well as the final destination of all religions that exist.
http://www.dlshq.org/discourse/may2002.htm
