They have also released an animated version of the transition:
"The new brand mark signals a clear purpose for our brand and it will be a badge for those who pursue a fuller life through fitness. We believe the benefits of an active life go beyond the physical benefits and impacts your whole self and your relationships with others," said Matt O'Toole, Reebok Chief Marketing Officer. "It is our symbol of change - an invitation to take part, and to unlock your true potential. It's not a logo, it's a symbol… a way of life."
Via the Logo Design Forums