Spiders, Mobile Site, and Serving alternate content

Will serving an alternative xhtml site to wireless devices hinder spidering

[seoDre]

Tried to move to the spiders thread but got denied..

I have a client that wants a mobile version of their site at the same root url as their current site. They want to serve an xHTML version of their site by reading the user agent and serving up a mini-site under their domain name. Will this cause any problems with search engine spiders and getting indexed or potentially penalized?

I personally don't like this idea, I think it would be better (for many reasons) to have it www.mobile.companyname.com, but they do have a valid business reason.

[seoDre]

Hmmm, was it something I didn't say?