Power 7 - revisited
The information about Power7 are still a little bit sparse, but it at least some fragments are public. So: It looks like, you are out of luck, when you expect to upgrade your pSeries 520/550/560/575 systems to Power7. According to this statement of direction there are just upgrades for the Power570 and 595. I find this a little bit strange, as the p560 and p570 are not that different from a technology point of view.