Such a project is newly underway, and (unlike many of the current exchanges) there is an impressive group of people behind it.
Following the events of April 2013 in which Bitcoin value dropped dramatically as a result of the short comings of existing exchanges it was decided that there should be a community driven and open source exchange. As such Buttercoin was born out of neccesity for this. Buttercoin allows the decentralisation of exchange between Bitcoin and other currencies.
Check out:
- http://www.reddit.com/r/Bitcoin/comments/1c7v6z/buttercoin_open_source_highperformance_bitcoin/
- https://buttercoin.hackpad.com/
- https://github.com/buttercoin/buttercoin
P.S. I posted an article tonight you might find interesting discussing the difference between Bitcoin and Bitcoin Exchanges, with the underlying point being that while Bitcoin itself is solid, we need to improve our exchanges! http://www.247btc.com/bitcoins/138/bitcoin-railroads-exchanges-ticket-booths/