Edwin - 9:42 pm on Aug 20, 2010 (gmt 0)
Having the exact match domain also brings more clicks (all other conditions being equal). I did a case study on this a while back, testing 3 Adwords ads against each other for the search phrase "electric bicycles".
The exact match domain got significantly higher CTR and visits than the other 2 domains I used in the test - and that was the only difference as the ads were in the same ad group (back in the day that Google Adwords allowed multiple domains/adgroup) and had the same wording, the same bids and the same keywords targeted.
In other words, in a fair A/B/C test with the only variable being the presence/absence of an exact match domain, the ad with the exact match domain pulled MUCH better than the other 2 ads.
It's a combination double-whammy of the searcher seeing their own search phrase "parotted" back at them in the URL, and also seeing it "up in lights" (exact-match keywords get automatically bolded in the URL) that acts as the hook to generate the extra pulling power...