Photo credit: secretlondon on FlickrWASHINGTON — Political advertising is reaching into polling places and even into the voting booth. That is one of three trends for 2010 campaign advertising identified by Peter Greenberger, Google's head of Public Sector Ad Sales. What's that, you say? Politicking is not allowed within 100 feet of polling places? How quaint. How very 20th century. Once again the law governs atoms, not bits….