The us.rd.yahoo.com/dir/home/cats/*http://dir.yahoo.com/Arts/ style links are not new - I think the format has changed a little over the years, but they've done redirects from the directory homepage to cats as far back as I remember.
Considering that there are thousands of external links to each category in the yahoo directory, that is not the reason.
Couldn't agree more. All those internal linking redirects use a 301 anyway so Google is still able to see them and count them in.
Why would Google treat Yahoo different than any other site selling paid links?
A web portal that provides news, search and a whole host of other user-friendly web outlets cannot be deemed inappropriate for having a directory. Creating "lots-of-links-r-us.info" and charging $5 a pop with no review has only one aim. The two are very different ... of course, I'm not saying that Google actually bothers to try and tell the two apart ... ;)
Did find it curious that MattCutts chimed in that early on a thread. Almost panicky? ;)