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Wirelessly posted (Mozilla/5.0 (iPhone; U; CPU iPhone OS 4_0_1 like Mac OS X; en-us) AppleWebKit/532.9 (KHTML, like Gecko) Version/4.0.5 Mobile/8A306 Safari/6531.22.7)

Many websites use third-party internet ad companies to handle their banner ads. Decent ad firms will at least keep the ads "relevant", like seeing ads for Sprint or Motorola on a site dedicated to iPhone users. Less scrupulous ad firms will let almost anything fly.(like the time that NYT had banner ads that were installing malware)

Clicker beware.
 
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