Can the Epson V700 be used with an Airport
You cannot scan over the network using the USB port of the airport express. It is only for printing.

Apple does not explicitly say that scanners are not supported, but it is not one of the official uses of the USB hub. I have not heard anyone being successful in this, and AFAIK there are no hacks/third party s/w to do this (like AirFoil for streaming audio).

I personally have tried, in vain. I have a HP all in one, but the Snow Leopard does not recognize the scanner functions. I have to physically connect the scanner for this to work.