MSI has made the first step in giving GTX 400 series owners more flexibility in obtaining higher than stock clock rates with its latest Afterburner software (1.6.1 Beta 4). The installation of this software together with a GTX 480 gives the ability to start tinkering with the voltages.
Shane has confirmed that the software is not restricted to MSI-only branded cards either; you can see in his latest article here that he used a GIGABYTE branded GTX 480 to test with and it worked a treat.
GTX 470 owners don't get the ability just yet, but don't worry guys, we've been informed there's another Afterburner update coming out within the next week or two that will make it possible to do the same on your card(s).
Obviously you'll want to keep things in check and make sure you don't go burning up your precious piece of hardware, but Shane has been told that with the stock cooler it's good enough to handle a voltage increase from .937 to 1.1v, but don't take that for gospel and keep your eyes fixated on temps before fiddling around.