Think of it this way whether the theme is for free or for sale, on the bottom right/left hand corner will be stated ” Theme Powered by (name/website url)”.

If this theme was pick up by 10,000 users what would be the outcome? Visually this on internet marketing perspect and you will know what i mean.

why should developers trust to him in their turn, selling their work on such conditions?

No reason at all. As soon as you licence your work as GPL, he can do what he likes with it. He doesn’t have to credit you, he doesn’t have to pay you, he can make major code changes without running them by you first, and anyone else who wishes can do the same.

Personally, I’m ok with that (I’m not talented enough to be too precious about my stuff, and as a hobbyist I’m not bothered whether I get paid or not) but I wouldn’t expect everyone else to be as laissez-faire about the prospect.

my guess is that this venture is primarily aimed at the developers who are/were selling sponsored links to cover their costs, and he doesn’t trust them not to sell their ‘allowed’ link to spammers.

if Matt doesn’t trust developers enough in this regard, then why should developers trust to him in their turn, selling their work on such conditions?

while the reports of the unique backlinks to a theme designer’s page in the Google Webmaster (former Sitemaps) console is not exactly the most precise way to count a number of theme installs on the site:wordpress.com, because it’s getting done by the third party (Google), and, of course, it’s nowhere close as a direct query against the Automattic database.

however, for nothing (as it known to me) else, backlinks currently are pretty good way to give to a designer at least an idea of an adoption of their themes on .com, also backlinks may help to reckon their revenues as well.

otherwise it may going to be exactly as with the (not existing yet) ‘Adsense Manager‘ on .com

Matt talks about credit at
http://photomatt.net/2007/11/01/wpcom-marketplace-idea/#comment-430158
http://photomatt.net/2007/11/01/wpcom-marketplace-idea/#comment-430256

The corrct proposal is for the the theme’s name and author’s name to be included in the footer, but not linked.

Matt, I’d like to hear your reasoning on this.

Obviously I can’t speak for Matt, but my guess is that this venture is primarily aimed at the developers who are/were selling sponsored links to cover their costs, and he doesn’t trust them not to sell their ‘allowed’ link to spammers.

If credit’s important to you, don’t touch this with a bargepole. There are plenty of other distribution channels out there.