When doing the tests with some of my blogs I seems to have noticed one thing which can be seriously important for Yahoo SEO.
It goes like this...
I do a post on the blog (well established blog with at least 100 pages indexed) and then for this keyword (usually an easy one) I am page 1 in Yahoo within 24 hours.
But then Yahoo sort of "junks" the blog post page and the page goes very deep, until Yahoo stirs the page for enough time and gets it back to almost the same position where it was during the first 24 hours after posting.
And with Google the same behavior, but without junking the page.
My bald statement - Yahoo is pretty much the same as Google, but it only has a time factor to kick off the "hurry up" SEO specialists. But then you still get the same results.