This might be one of those kind of obvious statements that elicits "face-palm" reactions, but more seriously, think about it.
When a company develop a commercial product, they typically will keep it under wraps, not letting anyone near it until it's done. While I hate to mention Apple, the iPad (or iPhone OS 4 update) are both great examples of this, as are a lot of their other products. They don't talk about them until they're done, which is great in a way for the typical consumer. You don't want to hear about something, and then not actually be able to get it for the next X months. That's frustrating.
And that is exactly the experience that has been seen on tmo a few times now - people getting frustrated about the unavailability of XYZ, be it a product (like an OS update) or even news about a product (like the ever-contentious subject of MeeGo on the n900).
This experience exists, of course, because information is out and floating around long before the product is actually due: the topic of the thread that sparked this post, PR1.2 for Maemo 5, was known (at least by me, in some form) when PR1.1 shipped in January, because a bug I was watching was marked "fixed", but "for the next update".
To get down to the point a bit, I wonder what the solution to this problem is. Obviously, not releasing information at all isn't really a plausible possibility for truly open development - but then, what?
I think that there are two solutions.
Firstly, the information that *is* released should be targeted. Obviously, since it's from a big company, it'll spread - but (for example) the announcement of MeeGo was assuredly premature, and even Day One was a total damp squib for a lot of people (even me: I was excited by it, but as a primarily applications developer, it wasn't all that useful). So obviously, the information that is going out needs to get to the right place. In that case, the OS developer community.
Secondly, that more information should be available, targeted at different subsections of the community. For the device enthusiasts, they should have rough ideas about what is coming, even if it's not details on features, a general idea would be nice. For the application developers, SDKs (and possibly even preview images or packages, if it's an OS release, Qt update, etc) would be lovely.
I don't have any firm conclusions on how this can be best managed, but I think with some thought applied to the above, it might be possible to get a little less confusion out in the wild.