Not sure if this helps, but Duane Forrester from Bing stated at a conference I attended recently that it is better to use one URL for your desktop and Mobile site.
Here is an article suggesting the same: http://www.seroundtable.com/bing-mobile-seo-14861.html
One thing he did say was that if I come to your site via my desktop and do a search, I would like to obtain the same results if I searched your site on my phone.
The article does state that in some cases you would want to have different mobile pages from your desktop version.
Also, how have you applied a 301 redirect for mobile pages only?