In Summer 2005 The promo version was shown on the Wubbcast Episode #33 months before the show aired. This was a presentation that the show would air on Nick Jr. in Fall 2006 (although it aired on August 28th, which was in summer). The promo's singer sounds different and mostly uses clips from the show's First 2 episodes, along with two noticeable elements that weren't used in the final version of the Episode A Tale Of Tails since it was still in the making. Wubbzy's voice sounded deeper in both the beginning and end, and there were a couple of unused clips of The Pilot seen.
Credit to Viacom Nick Jr. & Noggin I Own Nothing