How do I use the USB port on the Airport Express?

I have a Samsung printer plugged into my Mini's USB port and it work's fine. But I see my Airport Express also has a USB port. How is that intended to be used?

I plugged the printer into the USB port on the Airport Express but I'm pretty sure the Mini could no longer "see" it. What do I need to do in order to get the Mini to be able to see and access USB devices plugged into the Airport Express's USB port? Can I add a USB hub there and hang multiple devices off of that?

If it makes any difference, the Mini is a month old and the Airport Express is the latest model.

Thanks very much in advance,

Chris