From the introduction:
GraphGL is a network visualization library designed for rendering (massive) graphs in web browsers and puts dynamic graph exploration on the web another step forward. In short, it calculates the layout of the graph in real time and is therefore suitable for static files (exported GraphML/GEXF files) and for dynamic files (LinkedIn InMaps would be one such example).
As such, it is both a replacement for Gephi and a complimentary tool, similar to Seadragon, providing another method for displaying graphs in a Web browser.
A very good article that also covers technical issues of graph rendering in a web context.
A project to watch, or better yet, to help advance.