An interesting observation that we made while talking with people how they use social media, is that people either use and like Twitter a lot but not Facebook, and vice versa.
We are not sure why this is the case. One possible explanation is that using regularly both Twitter and Facebook just takes too much time, and people tend to focus on one application.
Another explanation could be Twitter and Facebook are very different applications and appeal to very specific personalities, i.e. there people either have a "Twitter personality" or a "Facebook" personality. However, we weren't are not what these personalities are. This is one question we want to explore further.
Another interesting question is whether Twitter and Facebook cover all "online social networking personalities", or whether there is room for another social networking application that appeals to people who are neither on Twitter nor on Facebook.