Second Life is prohibiting the offering of interest or any direct return on an investment, whether in L$ or any other currency, from an object such as an ATM within Second Life, without proof of an applicable government registration statement or financial institution charter.
That's a mouthful, but it boils down to heavier regulation of money that can be made in Second Life--more importantly, how that money is made. It sounds an awful lot like a governmental role, but it's an important step for the virtual world, especially if it would like to avoid actual regulations from the real government. Second Life has in fact been receiving complaints from residents regarding banking activity, and in order for Second Life to remain the entity that it is, it has to self-regulate to a larger and larger extent. Part of what made Second Life an almost-household name was the bickering about virtual property that eventually led to a real lawsuit (in real life).
So it's no surprise that Second Life administrators are taking measures to avoid any questionable tactics from going down when it comes to money that exchanges hands. The issue is in part due to the banks that act as third parties, operating within Second Life. Just as Facebook's open platform lent itself to a flurry of advertising networks specific to the application train, Second Life's money-making opportunities have made it more attractive to a wider array of people. More people means more diverse behavior, and that's not always good.