Winamp 3 is no more. AOL's Nullsoft division has decided to discontinue Winamp 3 and return to enhancing Winamp 2 for the time being. A future "Winamp 5" will eventually become the next generation Winamp.
Winamp 3 was a very ambitious upgrade of Winamp. Rewritten almost entirely from scratch, it contained a new object oritend development language/environment known as Wasabi that would allow developers to create all kinds of things.
Unfortunately, such power requires memory and other resources which didn't appeal to Winamp's core user base which used Winamp because it was fast and light.
Winamp 3's cool skinning engine, however, is being brought to Winamp 2.