mememax - 11:31 am on Dec 16, 2011 (gmt 0)

I'm not a real great expert but, have your considered exclude the m from the rule above?

RewriteEngine On
RewriteCond %{HTTP_HOST} !^(www|m)\. [NC]
RewriteCond %{HTTP_HOST} ^([^.]+)\.domain\.com(:80)?$
RewriteRule ^$ /section.php?slug=%1 [QSA,L]

and below try with the rules you've already tried.