Piledriver is AMD's incremental update of the Bulldozer CPU core. Their estimate is a 10% improvement over Bulldozer, but that estimate was given before Bulldozer was released in the retail market.
If that increase holds true, then the Piledriver series will be roughly equal to the 1st generation of Core i3/i5/i7 CPU. Sandy Bridge is Intel's 2nd generation Core i3/i5/i7 CPUs. Ivy Bridge will be the 3rd generation and it is expected to be released sometime in April/May.
Was it april 8th or april 9th? I forgot lol