Pollution in Beijing doesn't appear to be getting much better in the run-up to the Olympics, now just 68 days away. James Fallows posts pictures on his blog from time to time. Here's his most recent, taken May 27th:
Here's a picture of Hong Kong's pollution problem, taken on our most recent trip there five months ago:
Many more photos from Hong Kong are featured in EarthPhotos.com's China Gallery.
There is a discussion of Beijing's Olympic-sized pollution problem on Jaunted - The Pop Culture Travel Guide .