Former Viacom CEO Frank Biondi and former Nextel CEO John Chappel will join Carl Icahn as the newest additions to Yahoo’s board.

All eyes are on Icahn and his gang. The three amigos will need to start making changes to placate shareholders soon because if they don’t, it’s likely that nobody on the board will. The three were part of Icahn’s original proxy slate that ran under a campaign to sell Yahoo (YHOO) to Microsoft (MSFT). Icahn dropped the fight in July in exchange for three seats on the company’s board.

Shareholders are still waiting for Yahoo to come up with a plan that will drive up the stock. Since mid-June, when Yahoo announced that talks with Microsoft were over, the stock has dropped roughly 20% in value and has hovered in the low $20s. Microsoft had originally offered to buy Yahoo at $31-a-share. Earlier this month investors re-elected Yahoo’s eight incumbents. But investors signaled their unhappiness with CEO Jerry Yang and chairman Roy Bostock. Yang received 66.3% of the votes while Bostock received the least, with 60.4% votes.

Wall Street isn’t convinced that Icahn and co. can do much to turnaround Yahoo. Says Thomas Weiser Partners analyst Christa Quarles, “Yahoo needs someone to help fix the business, and I don’t know if Icahn has the background to do that.”

Icahn has yet to reveal what his plans are to drive shareholder value for Yahoo beyond selling part or all of the company to Microsoft. The corporate raider has most recently pushed for management change at Blockbuster (BBI) and Motorola after securing board seats at those companies. Last year, Blockbuster CEO John Antioco agreed to step down after Icahn initiated a campaign to cut his salary. After Icahn won two seats on Motorola’s board in April, he persuaded the company to dump its cell phone division and was instrumental in pushing out former CEO Ed Zander.

Chappel, who is president of Seattle-based private equity firm Hawkeye Investments, was unavailable for comment. Biondi, a senior managing director of private equity firm WaterView Advisors, responded in an e-mail that he does not comment on boards that he serves. Biondi is currently a director of five other boards, including Seagate (STX) and Cablevision Systems (CVC).