Capcom is going to release a new Street Fighter 20th anniversary artbook. As of the time of this article, it will only be available in Japan. There's no word on an American release.

Aside from mostly Japanese text, this should be something worth importing if you're really into the artwork from the series. The tentative price is about $37 USD (with tax included), although you'll probably pay a bit more to import it. Release date is April 4, 2009 and it's said to be 320 (!) pages total.

Here's some photos of the book from Capcom of Japan's Street Fighter 4 Blog.

You can also see a few more shots here.