Big changes are afoot in the Twitter executive roster today. According to All Things D, former chief financial officer Ali Rowghani is being made chief operating officer. That's the same post that belonged to CEO Dick Costolo until October of 2010, when he took the top spot from co-founder Evan Williams. After leaving Pixar to join the company in 2010, Rowghani developed a reputation for being heavily involved behind the scenes at Twitter, including contributing to its monetization efforts by offering ideas for its Promoted Suite of ad products. Rowghani’s former CFO position will go to ex-Zynga treasurer Mike Gupta, who is leaving that company after just over a year.