The Skype Garage post explains:Starting from this version we've included the new Super Wideband Audio codec. This is our second in-house built audio codec especially designed for calls over the internet with superb quality. The Super Wideband Audio codec will help you most on lousy network conditions and when you have lower bandwidth available, although it also improves quality in normal conditions too.
The codec is codenamed "SILK" and it aims to improve the audio out to 12,000Khz and has several improvements. Skype Journal covers the SILK codec benefits nicely in this post.
So if you want the Super (Duper) Wideband audio codec, head to Skype.com and download Skype 4.0. If you want a Super Duper Weenie and a Coke, head over to www.superduperweenie.com for directions.