It's also dishonest to imply that Google is not itself a marketing company.

I did take me a while to realize that Google long since made the pivot from tech company (the search engine that started it all) to ad company (where they make their money). After you look at the profit numbers, it really isn't all that interesting how they spin what they're doing -- or what they do to maintain a customer base that buys ads (such as creating a smart phone platform to stay relevant).

I'm not actively going out looking for other direct marketing companies in order to give them my data -- why would I do so with Google?

Google's been an advertising company since the day they realized they could make money off of search.

If I run an ad campaign, and tell Google to show my ad to a specific demographic of users, then I know that anyone who clicked on that link is (most likely) in that demographic.

In Gmail, clicking the "Why the ad?" link pops up this message:

"This ad is based on emails from your mailbox and information from your Google account. Ads Settings puts you in control of the ads you see."

So clearly they are using your Gmail information for marketing purposes. Are they selling it directly? No. But it seems dishonest to me to claim that they aren't selling it just because there is a middleman (Google) between the marketer and Gmail user.

Newsflash: Google is a marketing company!

But that doesn't mean that they give or sell your data to other companies. In fact, that would be incredibly stupid, each bit of data you can sell only once, while as space, you can sell every day.

Is there really such a major difference between you giving your data to your email provider who then sells it to other companies or you giving data to your email provider who then uses it very much the same way these other companies would do?

One major difference is that data is sold tends to get a life on its own. Company A sells to B, B to C, etc. Before you know it, your e-mail address/phone number is in the hands of many companies.

Google is different in this regard. Since they don't sell raw data, it's easier to opt-out (remove data via the Dashboard[1], delete your account, etc.).

[1] http://en.wikipedia.org/wiki/Google_Dashboard

Fair enough, that is indeed a – possibly major – difference, although Google department A sharing data with department B, which gives stuff to department C could be argued to be similar, as the size of these departments easily match those of other companies.

Correct … but do not forget that there is Google Apps for Business too where you are not shown any ads.