There is a lot of discussion on forums regarding an update to the Yahoo! Search algorithm. To me, it just doesn’t matter as the amount of traffic which is pushed via Yahoo! Organic is a fraction of what Google sends. Looking at rankings, my test domains are showing strong increases in ranking, includes a lot of new Top Five entries. The problem is, the traffic from these listings is pathetically weak.
For example, we moved from #7 to #3 for the term “web marketing” and that increase brought a total of seven clicks over three days. That’s right, 7.
Word has it that Microsoft is close to signing a deal to buy Yahoo! Search and Yahoo! will go back to using Google for their search results with a mix of directory listings too. Let’s hope so, the organic listings in Yahoo! have been historically weak and we need another reason besides PageRank in Google to have a listing in the Yahoo! Directory.
The main reason I started the SEO Revolution was out of frustration. Frustration at all of the lies and misconceptions that are posted in forums, given as advice in teleconferences, and even taught in live workshops. "So why didn't all of this work?" " Why wasn't my site successful?" " Why am I still stuck in a rut?" 
Well, Micro-hoo is much more complicated than you may think.
I believe Yahoo bring very few clicks and I am not sure if they are less than 1/3 of Google ratio. In my case maybe less than 1/10.
Yahoo changed the algorithm & I have lost few Keywords Ranking from top position in Yahoo.