I hope that is the case but I can't help but think of how ads feel in Facebook when they enter the "timeline" it's like you're watching your favorite television program and a really obnoxious commercial comes on - makes you want to leave the room. Or in this case leave Facebook. So I really hope that Ben keeps that in mind.
Tasteful—No flashy banners or pop-up ads. Transparent—We’ll always let you know if someone paid for what you see, or where you see it. Relevant—These pins should be about stuff you're actually interested in, like a delicious recipe, or a jacket that's your style. Improved based on your feedback—Keep letting us know what you think, and we'll keep working to make things better.
I have to say though, that it's probably about time. How else does Pinterest make money if it doesn't allow ads? And if you want to keep good thing going you'll have to start generating serious revenue at some time or another.
From the standpoint of a potential advertiser, I am excited. I don't want to alienate anyone with my ads but at the same time with all the pins it's hard to keep anything at eye level in any category on Pinterest. I'm looking forward to the prospect of pushing my pins to the top - although you and I both know that only the pins that generate the most "repins" will be the best content on Pinterest. As it should be.
So to Ben and the rest of the Pinterest crew - best of luck! All of us internet marketers (and avid pinners!) will be watching.