Hoping that Wall Street likes its products as much as Facebook users do, Zynga ??? the company behind hit games such as FarmVille and Mafia Wars ??? is poised to file for an initial public offering by the end of next week, says Kara Swisher at All Things D. Investors have been eager to buy into social media companies, and the stock of last week's IPO darling, LinkedIn, remains around $95 (double i