The leaders of Corrections Corp. of America say they are ready to convert the company into a real estate investment trust and have made the necessary organizational changes. All that's missing is word from the Internal Revenue Service approving the corporate overhaul. That approval matters to investors because, beyond the ongoing tax advantages of a REIT switch, a one-time payout of more than $700 million is at stake. No thumbs up from the feds likely means CCA shares (Ticker: CXW) will give up some of the ground they have gained in the past year.