More modern look coming this fall.
New Airport Express with 802.11n Next Week?
MacGeneration points to an prematurely updated description at the Swiss Apple Store that describes 802.11n Wifi support.
The Airport Express currently supports 802.11b/g networking only. 802.11n offers greater performance, more range, and improved reliability over the older Wifi standards. Apple has been including 802.11n in their computers since early 2007.
Airport Express allows you to stream your music from iTunes, share a printer wirelessly, and share your internet. More details about Airport Express itself at Apple's site.