Its really my challenge also. At first I think its OK with big brands like BBC, CNN.
But in Vietnam, I just find that there's only one site "tested" by Google! But its not our company's site, the leading online news (highest pagerank, most trafficked, most updated)... The only clue is that the loved-by-Google site is among the most well-known offline newspaper in VN though (that I doubt that Google engineers are aware of)
Funny that the "tested by Google" site is not well-optimized as our company's one (thats why they even contacted me to do SEO for them but I refused weeks ago).
I'm seeing something similar, but not exactly the same. [flickr.com...]
So, yeah, probably just a test.
I'm not sure that CNN is doing anything special. There's certainly nothing special in the code on their front page and Google is grabbing the title from article's page, not the abbreviated titles on the main page. It's not grabbing the titles from their RSS feed, either, although it is listing the same top 3 stories in the feed, so... that might be something.
Other than that, it's probably because they're a big name.