Removing format from routes

Hi all,

We're currently using format to serve up multiple versions of the same
site (e.g., www and mobile). The choice as to which to serve is
either set as the format GET parameter or via the subdomain of the
request. What I'd like to do is only generate one set of URLs from
routes. Right now, depending on the site the url_for call is made
from, we could have two URLs differing only in format that point to
the same resource.

Any help would be much appreciated.

Thanks,
Kevin