To join two or more sounds, select the sounds and then select "Join" or Ctrl+J. This might be useful for quickly removing silence from adjoining clips.
For example, Soundwarrior records an hour long radio show and wants to get rid of the ads for his own personal use. He loads in the show and then cuts all the ads out using the Cut or delete command. He then selects the entire track by right clicking on the track header and selecting "Select All Sounds". He then presses Ctrl+J or selects "Join" from the "Sound" menu. All of his sounds are now right next to each other with no silence gaps and ads!!
Note that if the sounds are on separate tracks, they will not be joined. Sounds will only be joined with sounds on the same track.