You can delete tweets, but not change their date, so "I told you so" is already possible in Twitter (and in probably a lot of other social networks, HN, for exa

You can delete tweets, but not change their date, so "I told you so" is already possible in Twitter (and in probably a lot of other social networks, HN, for example). Aside that, I like the idea very much and have thought about implementing it myself in many different ways. However, I think that immutability is more a feature than a product, if you don't mind me quoting Steve Jobs on Dropbox.