"Companies spend billions of dollars annually to promote their products, and the film industry is receiving a lot of that money to shamelessly put unrelated products ‘naturally’ within movie scenes. It began as somewhat of a subtle attempt at subconsciously influencing the audience’s thoughts and opinions of a product. Today this annoying marketing degree ploy mutated into a terrible affliction that often seems to grow films into long commercials."

30 Rock McFlurry

it Thing has a great little article about product placement in movies.
"The 5 Degrees of Poor Product Placement Forced by Marketing Companies in Movies". It's worth a read.