I think this would be cool too.
Detecting the browser wouldn't be that tricky... you could just embed a little code in ubbt_header.tmpl:
if ($HTTP_USER_AGENT == "mobilebrowser"){
echo "<link rel="stylesheet" href="mobilestyle.css">";
} else {
echo "<link rel="stylesheet" href="$stylesheet">";
}
If you wanted to use entirely different templates and not just stylesheets, it's a little tricker but not much (I did this on an old version of UBB). If I can help let me know.
-Y
