Good point by sherifnix.

For hardware upgrades it makes sense for companies to keep things secret, because if it comes out you risk everybody stop buying the current hardware and the cash flows stop until you finally deliver. (This is called the Osborne effect - the announcement of the successor to the Osborne-I killed the company).

For software, on the other hand, announcing new or upgraded versions can have the opposite effect: People buy the hardware in anticipation of what they can do with it in the future. Many companies realise this, that's why the phenomenon 'vaporware' is so common in the sw business..
Some middle ground would be good I think. Nokia should feel free to announce non-vaporware future software upgrades.