I noticed that Twitter puts ads by DoubleClick on its user pages in the Japanese translated version. You could check it out yourself by going to my Twitter page and then selecting Japanese from the language dropdown list. You need to be logged out of your twitter account in order to see the language selection box.

A screenshot of the page with the ad:

Well we all know Twitter needs a lot of support for their current problems, so a small ad box wouldn't upset its users I guess. Atleast it doesn't bother me although I don't have many Japanese followers. What about you? What are your comments about the ad box in Twitter?