Edmodo started off as Safe Social Networking for schools but they quickly added a (simple) grade book, quizzes and polls turning it into something more like a VLE or Learning Platform.
Their latest news is that they are going to have an app store for learning contents on the platform. This sounds interesting as decent content is always what is missing on any learning platform and finding, trying, paying for and installing new content is always too complicated.
So will Edmodo turn out to be a free VLE on which you can run your school? First thought – the grade book allows a numeric grade only ie, no A, B C or 5a, 5b, 5c. Second thought. Material and assignments are published in reverse chronological order ie in the conversation stream. There is no structure for courses.
So far I would say its not replacing a full VLE yet.