I can't say I've looked at many those dev. diaries, but they look as normal dev. diaries and not roadmaps. As I see, they combination of several things:
- Already done features just before the release
- Vague plans - areas where they identify problems but don't post solution yet
- Work in progress - things they currently work on, but could reconsider in the future (I've seen the word "reconsidered" in Victoria dev diaries as feature status, but I don't know how common it is)
So, once again, why I really love those developer updates, that's a bit different form of communication.