ActivePapers is a framework for doing and publishing reproducible research. An ActivePaper is a file that contains code (Python modules and scripts) and data (HDF5 datasets), plus the dependency information between all these pieces. You can change a script and re-run all the computations that depend on it, for example. Once your project is finished, you can publish the ActivePaper as supplementary material to your standard paper. You can also re-use code and data from a published ActivePaper by using DOI-based links, although for the moment this works only for ActivePapers stored on Figshare.
I consider this first release of ActivePapers quite usable (I use it, after all), but it's definitely for "early adopters". You should be comfortable working with command-line tools, for example, and of course you need some experience with writing Python scripts if you want to create your own ActivePaper. For inspecting data, you can use any HDF5-based tool, such as HDFView, though this makes sense only for data that generic tools can handle. My first published ActivePaper contains lots of protein structures, which HDFView doesn't understand at all. I expect tool support for ActivePapers to improve significantly in the near future.