Atlanta Firm Caught in Southern Company/Mirant Spat

Mirant, the Southern Company's energy trading and supply spinoff, is now in bankruptcy and suing its former parent for allegedly dooming its existence by failing to properly capitalize it. What's bizarre is that the prestigious Atlanta firm of Troutman Sanders represented both the Southern Company and Mirant in those negotiations. I don't know enough about the deal or remember enough from my professional responsibility class to remember if this type of representation is actually unethical. But such representations can easily spiral out of control and create an appearance of impropriety. I know greed is good and greed works, but shouldn't law firms think twice or thrice about representing both sides in the same transaction?