Hello! A smartphone like N900 is a multitool. Other people sometimes pick up my phone to check what time it is, use the calculator etc. I think that is OK.
But SMS is private communications.
Every time there is an unread message there pops up a sign saying that there is an unread message and who it is from.
It is not possible to turn that off. I recently gave away my iPhone because of the same problem, but my N900 does it too!
I would like to set the device so that nothing happens when a new message arrives. It should be nescessary to open the messages application to see if there are new messages.
I guess there lies a programming effort behind the device announcing that a new message has arrived. It would be ideal to be able to turn that on and off, but I would be happy also to find and delete the files responsible for announcing incoming messages. I posted this om swedish maemo and several members had the same problem but nobody knew how to solve it.

Interesting question. The instant notification of SMS's is rather a fundamental feature of the device, but maybe it's hackable. Does anyone know what process controls the notifications? If it's a separate process then maybe it can be killed. If it's part of hildon-home then hopefully as its open source this can be modified if desired.

One could disable GSM radio and enter tablet mode. This way no SMS will arrive until GSM radio is enabled.

Yes, that would be a kind of solution, but it involves sacrificing some functions temporarily.
It would be more desirable to keep the function but disable the flagging.
Most friendly people would never open the inbox of somebody else without asking, but if it pops up it pops up..
Per.

In theory one could make a program that listens for the sms (and why not other IM) notifications on the DBUS and somehow figures out the window the popup is in and closes it.

The "somehow closes" part is the hard one, the notifications should be easy to hook into (see telepathy DBUS apis).