Woldhowl uncovered another in your face case of link selling by Google itself:
wolf-howl.com/google/google-gi ...
It's very similar to the W3C case.

Just look at the page:
google.com/checkout/m.html

It's worth noting that all the links under "Browse additional stores" are rendered using JavaScript from the below Google Spreadsheet feed, so no guice will be passed to them...

spreadsheets.google.com/feeds/ ...

(I guess the companies with their logos at the top of the page, however, will be getting some link love.)

So now you're not allowed to link to your customer's websites? Many sites feature testimonials, list of clients etc. Google didn't sell links because those companies don't use Checkout to get a link from that page.

Here's the cached version of the page:
66.102.9.104/search?q=cache:ww ...

I think one of the things you've got to consider here is whether those companies signed up to be a Google Checkout partner purely to get that link back. I think the answer is quite obviously no. Would they still use Google Checkout if they didn't get linked to? I would reckon so... in which case, I don't think Google can be accused of selling those links.

That's what I said.

<<Google didn't sell links because those companies don't use Checkout to get a link from that page. >>