We have built what I guess is a P2P distributed ledger. Here's the sales pitch http://concordatablog.wordpress.com/tech
The inbuilt rules engine is trivial/crude. The key matter for us was to enable equitable negotiation of a record==contract within a private, but dynamic, network. This part is working pretty well now, so I'd like to make these contracts a bit smarter.
So I need to get my head round solidity and also how we can be more creative with blockchain. Can I, and does anyone else, use Solidity to perform validations and triggers outside of the Ethereum platform.