So what seems to be the problem? Yes, skype have (Or at least had) online history. But, since I can remember there was always something wrong. Not only on n900. It looks like skype saves only part of messages. And this is not all. When you are online and the person who you chatting to is not, there is high possibility that mentioned receiver will never get you msg. Or, this is better, the receiver will get you message straight without notifying or so.