Robert_Charlton - 6:01 am on Jun 13, 2012 (gmt 0)
My knee-jerk reaction is to say "Google feels you shouldn't make them". I'd agree with that.
In general, I agree with that too. Note, though, that there are some exceptions.
In one I know of, a brand is a proper name, and at the time I dealt with it some years ago, misspellings outnumbered correct spellings two-to-one. That ratio is hard to ignore. If you type far enough, Google currently will return both in Suggest/Auto-complete... but it still suggests the misspelled version first.
I found that in targeting the name(s) for ecommerce, putting Brandname/Brandnome in the title was actually the most expedient way to handle both spellings. If you're very patient, you could also rely on inbound links. If you wait long enough, natural inbound links will ultimately end up with misspelled anchor text. You may not outrank sites, though, that misspell it purposely. It's a competitive brand.
It's been a while since I've done this, but using both should still fly. I have a client site where I handle alternative product names this way (the idiom changes over English speaking countries), and we've done fine for both searches.