I am not sure when this happened, but in the past when you did a search in Yahoo and a site with an RSS showed in the results, an "Add To My Yahoo!" link was present. The "Add To My Yahoo!" link was a quick way to enable Yahoo! registered users to subscribe to a site's RSS feed. But that is now gone. Or appears to be gone.
Conduct a search on search engine roundtable, you won't see the link there, you will just see the following.
So, does that mean Yahoo! cares less about RSS these days? A post I wrote back in July 2005 named Using RSS to Improve Yahoo Search Success praised Yahoo!'s RSS approach. Here is the image of the SERPs from that post.
So where did it go? Why did it go? Does Yahoo! not care about RSS feeds any more? So many questions.
Forum discussion at WebmasterWorld.