Thanks for reposting of my tweet Kathleen, and for the clear explanation of everything that went unsaid in my 140 characters about why people should be aware of the commercial nature of academia.edu. I like the way you’ve pointed out that people find Facebook and its ilk useful for very legitimate reasons, and that the challenges of creating something that reproduce those reasons are significant. As users of the web, we all use commercial services all the time. What’s important is to do so in an informed way. Too often with services that are collecting our data, it’s not clear to many users what use the collector will make of it, and that’s where much of the problem lies.