There is something in the making... Todd Howard said in an interview that he and his team are working on something big. We can only speculate about what this is exactly but many people (including me ) are hoping for Fallout 4.
There were no hints about a new Fallout game on Gamescom 2014 or E3 2014. In an interview Josh Sawyer could imagine a massively multiplayer online version of Fallout as the next game. He works at Obsidian and developed Fallout New Vegas whereas Fallout 4 will be very likely developed by Bethesda which makes his statement more a wish than news.
The Fallout 4 FAQ from the Fallout Wikia is a good starting point to find a structured collection of facts and rumors. In addition to that CinemaBlend sums up the rumors that are currently around. Rumors are steadily growing: In 2012 somebody met a few Bethesda employees in Boston that were researching the city for a new game. A leaked document in 2013 reinforces this rumor and connects The Institute which is mentioned in Fallout 3 to the Massachusetts Institute of Technology (MIT).
To be honest, I don't expect to hear anything about Fallout 4 before 2015. My first blog post about Fallout 4 rumors is almost two years old and I hope in the meantime Todd Howard and his team made some great progress on the game they are developing and of course I strongly hope that it's Fallout 4.