Got this off the Adult Swim message board. I don't have access to the sites to confirm:
Turns out Studiopolis is dubbing it. Someone found Tiger and Bunny's listing in the Screen Actor's Guild database and Studiopolis is listed as the studio responsible. To put this in context for those who are not aware, Studiopolis also does Bleach and Naruto Shippuden. They can burn through a dub pretty quickly. I would not be surprised if Viz was at least halfway through the series, possibly almost done.
I doubt it's THAT far into it. Another board had a post where someone said they saw Wendee Lee at Momocon where she said she had auditioned for Tiger & Bunny but hadn't heard back yet, was hoping to hear in May (this month).
Take it all with a grain of salt. Looked up this company on imdb.com and Tiger & Bunny isn't listed. It's possible that hasn't been updated yet and I can't confirm this, but that's what's floating around.
I wouldn't watch it dubbed, but once it IS dubbed, more people in the English speaking world will get/want to see it, which is all kinds of good things. :)
Three... two... one... Tiger & Bunny Over and Out.