Walter posts about the sample screensaver we've posted on MSDN. It's really slick: it'll pick up pictures and descriptions from any photofeed you have on your PC. Source is available if you want to tweak it yourself.
I've posted a compiled version if anyone wants to just take a look without having to compile it themselves.
Usual caveats apply: this is sample code, it may not work, it probably won't affect your computer in any negative way, but it hasn't gone through rigorous testing, so I don't know for sure. Your mileage may vary. Void where prohibited. No warranties expressed or implied). Download here.
Just unzip both files into the same folder and double-click the .scr file (after subscribing to some interesting photo feeds in IE7 Beta 2 Preview, of course :).
Some people have asked what's the point of a an RSS screensaver? Well, my response is that it depends on whether you think the notion of a picture screensaver is interesting at all.
If you accept that a picture screensaver is interesting, then a screensaver that is automatically updated with pictures from a photo feed is just cooler. If you don't buy into picture screensavers at all, then an RSS-enabled one probably isn't going to change that.