Keith,

The current RSS Newsfeeds module is pretty basic, and as such does not actually do a lot beside fetch the feed with a web request and transform it with an xsl that is quite basic.  The functionality to do what you want is not available unfortunately.  Some folks resort to using a custom xsl that includes coding to display info using an html marque tag, but that doesn't really get you there most times.  I've seen some 3rd party modules out there that do something like what you describe but not exactly.

I just use the basic module for what it is, and create custom xsl's when I need them. 

I'd like to see what you describe done, in fact have a vb.net newsreader that I built that reads a collection of feeds, displaying news elements 1 at time, like some of the more popular websites, like MSNBC and others that display them as new story summaries, changing them every 6 or ten seconds.  I've not coded it for use in DNN though, but it's a thought.  Probably very do-able with ajax too, but I've got no time to get to it.  So, maybe someone else will take it on (wink, wink, nod, nod, say no more, say no more...) ;-)