This is a strong case for using distinct landing pages for your AdWords campaigns. I've never been opposed to that -- it's good strategy -- but I don't like feeling obligated to do so from a competitive standpoint.

SEO firms are loving this.

So who's building a howfastdoesmypageload.com around the world application?

Alexa's "Overview" page for a website (rather than "Traffic Details") will give you Speed and Load Time stats. Not sure how accurate they are.

from http://www.alexa.com/data/details/main/ycombinator.com:

Speed: Very Fast (87% of sites are slower)

Avg Load Time: .8 Seconds

If you're in a competitive industry, I'm not sure how much effect this will have. The Quality Score only effects your minimum bid settings. For example, most of my minimum bids are $0.05 and I'm bidding $1.50 a click. Even if my load times are a bit slower than my competitors, I can't imagine they will send my minimum bids to $1.00. Even if they send them to $0.25, I don't think it will have much impact (hopefully).

This is about AdWords and effects those who advertise on search results pages and in the content network.

You're thinking of AdSense, which is a different animal.