Maybe you've read that I did some coordination on relicensing the old GATOS TV-Out code to make inclusion into the radeon driver possible (gatos was gpl, while xorg uses mit-license).

Now, shortly after that Alex Deucher started implementing tv-out in the randr-1.2-branch of the ati driver based on that code. randr-1.2 is the new and shiny stuff that will make future versions of xorg manage resolutions and output connectors much better. As you can see on the picture, today I played around with the new code and got it working (get Gentoo git-ebuild here).

As a short howto, on some cards (including mine), autodetection of the connector status doesn't work yet. You'll have to manually force the connector:

xrandr --addmode S-video 800x600
xrandr --output S-video --mode 800x600

This is especially exciting as it is the last features of my laptop that was missing for »full linux-compatibility« (some minor issues left, as the cardreader only reads sd at the moment, the modem needs a binary driver).