The FX-4130 was originally slated to be released in Q3 of 2012, alongside the FX-4100 as its slightly faster sibling. Compared to the FX-4100, it boasts a 200MHz boost in stock clocks and will Turbo boost all cores to 3.9GHz when under load, should you leave that option on. It has half the cache of the FX-4100, but does ship with a better stock cooler, the same one found boxed with the FX-8350. AMD has sent out a skewed graph together with their press release and it promises performance improvements in the range of 3-9%.
UPDATE: It’s actually just another Bulldozer core, not Piledriver-based. Sorry for the confusion guys, that’ll teach me to learn to double-check other tech sites more properly. I’ve edited the article accordingly.