hmm, alright, let's see. kate herself has confirmed that she's in bleach:
http://blog.myspace.com/index.cfm?fu...2-5c8671674796

she's also confirmed michelle ruff's role in an email to someone:

Originally Posted by Kate Higgins
thanks. um.... i'm playing karin, the sarcastic sister. it's fun. and i think michelle ruff is the other sister. and , oh , i forgot the guy who's ichigo. i'm drawing a blank. i'll write you when i remember!
k
that's here: http://www.bleachforums.com/showthre...yuri+lowenthal

ANN.com also has those two listed: http://www.animenewsnetwork.com/ency...me.php?id=4240

about yuri lowenthal, bleach7's webmaster posted this:

Well, I can confirm one more casting. Apparently Yuri Lowenthal is in the mix. I sent him an email on which part. He didn't reveal who, but he did say he was doing a minor character. He did confirm that Viz will reveal who is cast for what soon.

Yuri Lowenthal posted:
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I think they'll be doing an official BLEACH dub cast announcement soon, so I'm not sure if I should say anything, but I think you'll be happy with the casting. I play a minor role on the show. They (VIZ & Studiopolis) are taking great care with the series, and know that there are a lot of nervous and excited fans out there.
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that's here: http://boards.ign.com/bleach/b8101/120202932/p2/?19

as for steve staley, it seems to be pretty widely accepted that he's in bleach, but uh, i can't seem to find the actual confirmation anywhere. *continues searching*