iw is a new nl80211 based CLI configuration utility for wireless devices. 
Currently you can only use this utility to configure devices which use a 
mac80211 driver, as these are the new drivers being written - most new 
wireless devices being sold are now SoftMAC. List of mac80211 drivers: 
http://wireless.kernel.org/en/developers/Documentation/mac80211#mac80211drivers

iw requires libnl, which is also available at SlackBuilds.org.
