A Google Webmaster Help thread has someone pointing out that Apache, world's most used web server software, has a thank you page where they have do-follow links for sale. And in fact, Google, amongst other brands are paying $100,000 per year for the link - or maybe they are just giving the $100k to support the foundation and the foundation just gave them a link.
The bigger issue is the "bronze" sponsors just get text links, they cost $5,000 per year but some of them are pretty keyword rich anchor text links that DO follow link juice and ARE against Google's guidelines.
Here is a screen shot of the thank you page:
As you can see, there are links to airport rentals, casinos, travel sites, web hosts, promo sites and more - all pretty spammy. They are mixed in with links to Twitter, The Linux Foundation and more. If you look at the source code, you won't find the required nofollow attribute on those links:
Also, the same with the Google logo sponsorship that costs $100,000:
This doesn't cost as much as the $350,000 Chrome paid link but $100,000 isn't that cheap for a link.
Forum discussion at Google Webmaster Help.
Update: It looks like someone at Google may have pulled down the forum thread after I wrote this. I did not screen capture it as I didn't expect the thread to go away.