Neo-darwinism also known as the modern synthesis, or synthetic theory is basically Mendelian genetics and Darwinian selection merged into a theory of evolution. The mechanisms that it proposes are random mutation + natural selection. But it had been discovered that these mechanisms are not as powerful as the neo-Darwinians first thought they were, they added in genetic drift and that is now described as the main mechanism with natural selection.
The New synthesis does not deny that any of these mechanisms, but it says they are inadequate to explain the biodiversity of all life on earth, the new synthesis says that neodarwinism is incomplete. The neo-Darwinian framework is limited, many new mechanisms have been discovered which do not fit into such a narrow framework and in some cases contradict neo-Darwinism. Some things which pop into mind are developmental biology (evo-devo), genomics, epigenetics, ecology, symbiosis, hox genes, natural genetic engineering, niche construction, systems biology, horizontal gene transfer, panbiogeography... neolamarckism ... & many others... as mentioned they do not all fit into a narrow neoDarwinian framework.
So what is this new synthesis and where is it developing? It is hard to say becuase currently there is no unified new synthesis at present, it just seems to be many new ideas that have been presented by many different scientists. I was recently in a long email debate with 60 scientists! And they were all pretty much arguing over which of the new mechanisms are correct and which ones are wrong...
Gert Korthof whos owns the website www.wasdarwinwrong.com talks about how the new synthesis is becoming visible and lists many of these new ideas.
Dr. A.P. JHA, Professor of Zoology, who has nearly fifty published papers on genes and evolution to his credit in his book called as 'Genes and Evolution' has a seperate chapter for 'Modification Of Neo-Darwinism: The New Synthesis'