Thanks for the suggestion.

If you look at the comments in the QtLabBlog post which I mentioned (http://labs.trolltech.com/blogs/2009/09/03/multimedia/), one of the comments from one of the Trolls is:
The Qt 4.6 MultiMedia APIs are a continuance on the old familiar architecture offering media playback via Phonon. This solution/architecture will be supported and maintained for the entire Qt 4 series, but no substancial new features will be added.

The newly architected [QtMobility/]MultiMedia APIs, which this Labs entry is all about, target both desktop and mobile development needs, have an entirely new architecture and will ultimately offer developers support for Video/Audio capture, Camera APIs, Playlist Management, Playback, Radio and more.
I'm not sure if this means that in the long run we should look at what is now "QtMobility/Multimedia API", and not Qt 4.6 Multimedia API... Other posts suggest rather that they have different focus (Qt4.6 Multimedia: low level access to devices [flexible, but haunted with details], "QtMobility/Multimedia" higher level [more complex tasks] orientation).

So: yes, I'll try the Qt 4.6 Multimedia classes. But it would be nice to see the other side of the story too... If anyone manages to make QtMobility/Multimedia API work on Qt 4.6, or finds any more info (wiki? some forum/mailing list?) - please, let us all know!