You might want to have a look at Yahoo Widgets - widgets.yahoo.com. In some (some!) ways this app is even more useful than Dashboard, in that you can easily have the widgets right on the desktop - and you set them to be transparent. Download the app and then go to the Gallery and search for 'ticker'. There's a few RSS scrollers there. You don't need to press F12 or whatever to view them, they can be there all the time.
I'm pretty sure there is a hack of some kind to get Dashboard widgets to stay on the desktop, but I can't remember what it is. I'm using a combination of Yahoo Widgets and Dashboard and its great.
You would think by now that CNN and FOX would have an application made for windows and MAC that would allow you to have a ticker in-place of the desktop taskbar. Infact, I would like to see one that is constantly running, and the taskbar hides until you need it.