The thing is that all 3 search engines use pretty similar ranking factors.
For example Bing/Yahoo/Google all love the following:
1. Links from relevant sources.
2. Great relevant unique content.
3. Great on site design for crawler access.
4. All onsite SEO and off site factors, some small changes like the size of title tags/urls ect may be slightly different on each website.
You can also optimize for Bing webmaster tools for example you need to add every thing in a similar way to Google webmaster tools:
<cite>www.bing.com/toolbox/webmaster/</cite>
Also Bing Ranking information can be found here:
http://www.bing.com/community/site_blogs/b/webmaster/archive/2009/09/03/search-engine-optimization-for-bing.aspx
If you have not done this I would highly recommend it, you can even use keyword research from Bing.
I also agree with DMAC that Bing seems to favour EMD domains (exact match domains) more so then Google does, I have tinkered around with a few tests on Bing and that is evident.
Also Bing has more social data to play with so you even need to push social rankings harder on Bing as they have the Facebook data access, which Google does not.
I hope this helps.
Kind Regards,
James Norquay