I've been searching a lot to try and find some definitive answers on the best way to present content in a good way for mobile users without causing any seo problems.

As things stand right now, if I create a mirror of the site on a subdomain that has been adjusted to be mobile friendly as long as I robots.txt out the subdomain I shouldn't suffer from any dupe content issues. However, if I want to get traffic from mobile search engines then I need to let them in.

What's the best practice, to use robots.txt only to allow certain mobile search engines into the mobile site and exclude the others like googlebot? If so, where I can I get a list of mobile search engines.

As far as mobile sitemaps are concerned - has anyone had any success with them, have you had a site that is simultaneously listed in both the full index and the mobile index without any duplicate content issues?

thanks

dan