The Senate doesn't reflect majority rule based on population. California has 38.3 million residents, Wyoming has 600K residents [1] but both states have 2 senate votes. Due to this, Wyoming residents have much greater voting power in the Senate than residents of CA.
Edit: And since bills must be passed by both the House and the Senate, Wyoming residents have much more power over what becomes law than CA residents do. [1] http://www.enchantedlearning.com/usa/states/population.shtml