In studying the full range of Canon's catalog and their products, I came to realize one significant discovery (apology of being slow here) - Canon has a much wider selection of lens and has a much superior range collection. Take for example Canon's lead in offering the Pro's series EF 28-300mm F/3.5-5.6L IS USM (recently, I was told Canon extended their lead with a EF 28-400mm lens lineup!)
Nikon has been doing a lot of catch up recently and is determined to vaporize this gap. Its an interesting match not to be missed. As far as photography and camps go, I am but a consumer, taking the best among the pack.
Nikon D90 is indeed a ground-breaking piece of hardware and warrants its praise and long-term use. Not many rival DSLR (e.g. Canon 50D, Sigma SD15, Sony A700) even come close to its superiority.