I noticed when I type in my keywords on Yahoo, I don't show up. But Google I do. How do you get in Yahoo search results?
Yahoo puts more weight on on-page factors of a site/page like keyword density, keyword usage, anchor texts and the relevancy of those links, etc. read this [URL="http://help.yahoo.com/l/us/yahoo/search/basics/basics-18.html]Yahoo guidelines[/URL]
Yahoo and Google uses different algorithms to rank pages. The article Claudek suggested got great information.
yahoo is supposed to be easier to spam... people with lots of junk links will do better on yahoo, people with lower numbers of quality links will do better on google, but yahoo is catching up to google... google is also supposedly biased against commercial sites, but yahoo not so much