jaina 's interview in Anime Insider with Kubo Tite hits newstands very soon. Go out and buy a copy. In the meantime, here is a teaser. Kubo-sensei answered her question as to why Bleach is called Bleach.
"Is there a reason the manga is called Bleach, or is that a secret?"
KT: The Soul Reaper-the color that you associate with the Soul Reaper is black. But "black" is too straightforward. So I thought about "white," but just white is too simple. So if you put "bleach," somebody can associate that with white. So that's how Bleach came.
Thank you jaina for letting me post that little bit. And now we know!
ETA: And I wasn't far off from understanding Kubo's title either! Looky what I found that I wrote! From here. "Bleach, by its very title, tells you its about color transformations and possibly about the moral distinctions between Black and White...." YEY! KUBO AND ME--same wavelength, yeah.