The Shafe Report on P2P Computing. A good survey of the state of P2P that tries to identify where the gold is for new startups:
It is often said in computer circles that the people most likely to make money during a gold rush are the ones selling pickaxes and shovels (as an aside a recent report on small scale mining points out that miners actually spend most of their money on gambling, alcohol and prostitutes).
The point is made to justify selling tools to the companies searching for the gold. However, when the technology is defined by a standard or is provided by the industry giants then start-up companies need to focus on either filling any holes in the standard technology or providing vertical solutions based on the standard technology.
Start-up companies can offer products or service that solves a critical problem for decentralized applications, like resource discovery or reputation tracking. Novel solutions to these problems could be licensed by larger software companies to address shortcomings in their offerings.