I heard about this via the news box at mangaKabob. A free manga magazine is launching in Japan, Comic Gumbo, which will be entirely supported by ads. The only surprising thing here is that it had not happened already. The Japanese and US markets are different, but if an ad supported manga mag can make it in Japan, perhaps someone will try it here as well. Given the media hype about how manga in the US is attracting a lot of female readers (an attractive demographic), there could be a lot of advertiser interest in a free manga publication.
Categories