Qt doesn't have any specific means for handling SMS. This is done through other components. As far as I know, at the moment there are no publicly available information about handling SMS in Maemo 5.
Originally Posted by grasssu
To install basic subset of Qt packages in scratchbox:
To get the whole list of Qt packages:
apt-get install libqt4-dev libqt4-gui
There is a tutorial for a very beginners in Qt:
apt-cache search libqt4
and of course there are books available.