Looks pretty bad, but I've seen worse....I'd probably wait around till the turbo seals crap out, which they like to do often. Then when getting it rebuilt just sending a good exhaust side housing with it so the better of the two can be put back togather.
eh. it happens. its even worse on the ST185 as they have a close coupled cat...anyway, you can live w/it until the crack goes all the way through the housing (connecting the inducer to the exducer). when that happens, you probably won't be able to hold consistant boost and a bunch of other weirdness.