If done reasonably off to the side of the pages and not to flashy, I wouldn't mind.

Well, for monetary gain it would maybe benefit Nintendo. But we all know they have to focus on advertising themselves.

Please no...

hell no. Miiverse is clean. I'm happy with it

Ads for indie, eShop, and third party games.

Miiverse likely doesn't have enough of an audience to warrant any significant ad revenue.

iPhone/Android apps have a potential audience of hundreds of millions of people.

Wii U has a userbase of 5 million users, probably only 1/3 of whom check Miiverse with any regularity (I boot right into whatever game I plan to play).

Candy Crush Saga has been downloaded something like 500 million times. 

I would have to say no. For one MiiVerse is a form of advertisement to begin with. While it would bring in some money it may have an effect on the users.