Preamble: Here is my complete video review on Amazon.com that is now the most helpful critical review, thanks to your votes:-)
Here is part I of this review if you missed it. I recommend you read part I first to understand the context.
I confirmed that D90 had better noise performance in day-to-day use as compared to Canon 50d. Again, no lab tests, no controlled environment.. but just regular in-house pictures.. and I can see more chroma-noise with Canon 50d pictures. Also, no matter what I tried with the Canon pictures style editor, it was near to impossible to get the 'punchy' colors that nikon produces. In all fairness, Canon's picture style editor is a great idea, and it does help a lot too (see my blog here). But the limitations are with how we can only select and change 100 discrete/individual colors, and there is no easy way to just plain rotate the color cone for all the possible colors. I decided to return the Canon 50d for these reasons.. plus the fact that it started giving me lens mount errors right out of the box. Come what may, I have re-ordered the D90 kit (I know.. but at least I tried both and found out what I like).
I know I will miss the tack sharp live view and the hot-pixel-less sensor from Canon, but I have come to realise that what counts is the ultimate aesthetics of picture-taking, and Nikon D90 gave me that. I caught myself frequently comparing D90's output pictures with the 50d's. And no matter what I did, I always spent more time staring at and panning and zooming in the Nikon results.
I plan to deal with the hot pixels with Adobe Lightroom which automagically maps them out from raw images. Or I will write scripts to map them in batches from both RAW and JPEGs in Capture NX2 (yes.. I found out that Capture NX2 allows you to remap hot pixels even in JPEGS.. so you dont necessarily have to shoot RAWs to avoid the hot pixels. as is the common misconception!).
So if you have read this review so far, please know this: I chose aesthetic pleasure over technical (or specification) superiority.. a personal choice. And if I could change the star rating of this camera, I would now make it 4-1/2. The half points will still be gone for hot-pixels and inferior live view with no exposure simulation.
There. I lived through two great cameras, and embraced one. Its your turn now. Good luck.. and whichever you choose, make sure you like the end result.. and not just the camera's specifications or mega pixel count:-)