http://www.gameinformer.com/blogs/members/b/sakabato24_blog/archive/2010/12/14/is-it-the-end-of-anime-and-manga-bill-156-passed.aspx
Tokyo bans anime and manga. Well...technically not all anime and manga, but anything containing illegal activities (so no pirates, for instance) and anything containing "sexual acts which violate societal norms" which sure sounds like it would apply to gay relationships. And publishers are apparently already reacting by telling authors they won't publish stuff set in schools or featuring school uniforms--this includes reprints of manga they have previously published.
WTF
They haven't banned the anime itself. They've banned the SALE of it in mass-market stores. Which is the next thing to banning it completely as publishers and creators lose out on that income. If they DO want to put it in those stores, stuff that violates the ban must be put in the Adults section, which again, might as well be banning it.
This does not ban hentai, ironically, as it is already marketed as an adult product and sold in adult-only stores/sections of stores. It dooms Comiket, apparantly, as it affects doujins as well. They might try to hold it outside of Tokyo, but the problem there is there are no venues large enough to hold it.
Yaoi and homosexuality is certainly a targeted genre here. The illegal activity thing is, as been stated, vague. I don't think Japan as a whole would take too kindly to One Piece being nigh impossible to buy, and I haven't heard anything about it being affected. That whole part of it is more to address rape in anime/manga/doujin being sold in say, Kinokuniya. Straight to the adult section with those now. And yes, many of those were not sold as adult material before.
Since everything is "voluntary" at this point, it's all up to the publishers to clean up their act. The law itself is basically the government going, "you KNOW what's not acceptable, and if you don't clean it up, we're going to have to do this the way nobody wants to"
From what I've seen, when it comes down to it, it's a good thing being done in a terrible way. I'm not lamenting the end of the era KissxSis could be shown on TV.