Michael Barton has posted a brief essay on Open Notebook Science on his research web site:

As you might expect from the name, Open Notebook Science (ONS) has similarities with Open Source Software. The clearest likeness between the two, is the belief that by sharing and collaborating, more can be achieved than through secrecy and competition. An open approach to software development is proven to be successful: the greatest achievement is the development, and increasing adoption of the Linux operating system. On this foundation other applications like the Apache web server, MySQL database, and the PHP scripting language have been built, and the combination of the four is the engine running many websites, including this one. If ONS can enjoy a fraction of the success open software does, then science can only benefit.

He also discusses ONS on the February 2008 edition of Bio::Blogs. In terms of an amazing example of recent ONS implementation, take a look at Gus Rosania's 1CellPK wiki. He currently has 9 of his group members with notebooks and he is trying to make the activities in his lab as transparent as possible. Obviously this involves experiments but also group meetings and his meetings with colleagues. He has also been providing detailed descriptions, including background and literature reviews, of his group's projects. Of particular interest to my group is the description of our collaboration on new anti-malarial agents. Since we can track their activities and they can track ours in close to real time, it will be interesting to see if we can crack open all the black boxes of collaboration. I have heard the objection many times that there is not enough time for researchers to read each other's lab notebooks. That's absolutely true but that is not an effective way to use these resources. The point is to spend little time skimming content and as much time as required drilling down to details when a relevant post is discovered. With Wikispaces one can also just subscribe by email or RSS feed to edits of a particular page. I would expect the UsefulChem group members to at least subscribe to the malaria project page I mentioned above. Gus is also looking at displaying experimental results in Second Life and has been doing actual experiments on the physics of Second Life. See his blog for the chronicles of that adventure.