Domain extension question!!

Hi All,

I've been thinking about putting together a mobile directory for local businesses in my area, you know - a restaurant directory, beauty salons etc, etc. The basic premise is to create a mobile directory which would then take the viewer to the businesses mobile site.

I figured this would be a good way of introducing businesses to having a mobile website as not only will they be in a directory but they will also have the mobile site for anyone finding them organically on Google etc.

For the directory, do you think it would be OK to have a .mobi extension or would you suggest having a .co.uk (or similar) and then create a mobile sub domain?

I ask because I am not sure how the Big G would view the .mobi extension and whether it would rank alongside a .co.uk or .com.

I'm assuming that it would be no different to get backlinks for the .mobi extension than it would be for any other type of extension.

If I can help it I'd rather not have to go through the time in building an actual directory first, I'd rather just focus on the mobile directory.

Any thoughts on this?

Thanks in advance for your assistance,

Scott