It really does appear that the Drama concerning whether or not the stormraven is going to be given to all the chapters in this coming white dwarf is resolved. Enough people have seen the article now, and all say the same thing.There is nothing in there to suggest it is allowed in the other space marine armies. This has been confirmed a couple times and even once by a reader here. Thanks Ianc.
It seems the extra drama might have been nothing more than a ploy at the moment of Wayland Games and some others to get more sales. I am not going to say that they were being malicious or misleading, only that they are probably wrong. Could there be something in March White Dwarf?, I hardly think so, but it is possible.
What does this leave us with? A Stormraven only being able to be used by Blood Angels and Grey Knights. Technically anyone can use them if playing apocalypse, so don't be dismayed at actually buying one for your space marine army. Don't forget that in friendly games, you can play with whatever as long as your opponent says OK and agree.
There is also the possibility that in near future we will be seeing new (optional?) rules for fliers. Everything points to the Stormraven as being included in that, so if the Summer of Fliers is a separate supplement, or even a white dwarf article, it is possible that we can see new rules for them there. Even the possibility of allowing the Stormraven in other chapters if playing with these rules.
Lastly, it is very possible that the stormraven and even the flier rules are being put to the test. GW actually putting the flier rules out as optional so that they might be included down the road for 6th edition if things go well. Since we all know that the Space Marines are always the first codex, it is very possible the Stormraven could make the grade and be in it. We have seen examples of this in the past with other vehicles.