In the field of SEO, Google’s search engine dominates the market. But what about other search engines? Yahoo and Bing, despite not being as popular as Google, can still send your website massive amounts of traffic. Many of the on page and off page search engine optimization techniques are the same for all search engines, but some search engines place more weight than others in certain areas. Bing, Microsofts replacement for MSN, heavily favors sites that have proper validating HTML code. Off-page, Bing favors sites that utilize social networking and social bookmarking sites. Bing also likes sites that link to lots of relevant external sites.
Heres in interesting article on SEO techniques for Bing:
On-page and Off-page Bing SEO Techniques