Brian Gryth

I think Scott Berkun has the best definition, "significant positive change." I also like Tim Brown's "good ideas well executed".

It is, however, worth noting that if you really care about innovation you should read Berkun's book "The Myths of Innovation" (Amazon link). The book points out the significant problems related to how innovation is treated and view. The reality of innovation, like many things, is not how it is portrayed.