IPFS stands for the "inter-planetary file system". IPFS is a bold attempt at evolving the Internet's infrastructure.
The aim is to have Fedwiki running as a pure Javascript application (no custom server required) and served by IPFS to allow a fully decentralised platform.
Here's how Juan Benet (@juanbenet) describes IPFS:
Quote by Juan Benet
IPFS is a global, versioned, peer-to-peer file system. It combines good ideas from Git, BitTorrent, Kademlia, and SFS. You can think of it like a single BitTorrent swarm, exchanging Git objects, making up the web. IPFS provides an interface much simpler than HTTP, but has permanence built in. You can also use it to mount the world at /ipfs.
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Here are some introductory videos, or just head over to GitHub and give it a try - GitHub 
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YOUTUBE 8CMxDNuuAiQ
An overview and demo of the go-ipfs alpha - GitHub
Below is a Talks at Sourcegraph @juanbenet gave about his project, "IPFS: The Permanent Web" (slides and video):
YOUTUBE Fa4pckodM9g Juan Benet discusses his project, IPFS, which is a global, versioned, peer-to-peer file system that combines ideas from Git, BitTorrent, Kademlia, and SFS. Published on 21 Jul 2014
Filecoin is the sister protocol of IPFS. While neither protocol depends on each other, they are perfectly complementary. IPFS handles high performance distribution of objects; Filecoin handles incentivising the world to backup/seed objects.
IPFS is a distributed file system that seeks to connect all computing devices with the same system of files. In some ways, this is similar to the original aims of the Web, but IPFS is actually more similar to a single bittorrent swarm exchanging git objects.