The first website I created about 4 months ago has been listed in all of the major search engines since the first couple of weeks. I haven't done any sort of SEO with it, since I was still learning (and still am). What was strange to me is that Google has been sending me traffic for awhile now. They were actually one of the only engines sending me traffic. Now all of a sudden I look at my statistics page, and Yahoo starts sending me traffic these last couple weeks, now double what Google is sending me. Does it just take longer to get ranked in Yahoo's engine? Why no traffic for months, and then in one week, my highest source of traffic?
I was paying $49 per year for Yahoo basic account which ensures your site is included faster and visited by bot on a regular basis but suddenly my site dropped down in rank because the site also had an account with Google. It's a competition story but don't know if it's fair.
If your site created the right ammount of backlinks over those 4 months yahoo must have noticed and started crawling your content. It is alot easyer to get into google then yahoo atleast thats what I have noticed from my experience It took me months to see some traffic from yahoo. I believe yahoo only starts listing your site when it gets good backlinks and decent traffic and you might of reached the right point
I don't know if Yahoo is still relevent or not...My search engine traffic from yahoo is around 5%.. Very poor..
Focus more on the On Page SEO and also make sure that you link to DMOZ, this huge directory has maintained its worth after many algo tweeks from both Google and Yahoo so go for it.