3) Authorship: "At LII we're very skeptical of web sites with more than a couple of typographical or grammatical errors."
Grammatical verification is the logical extension of trend number 2. If you're someone with any expertise, you should have acquired some basic communication skills along the way to becoming an expert. Those skills ought to include grammar skills. If you don't have the skills or the time for this, I again recommend you hire a proofreader to edit your text.
For more technically minded SEOs, this is the human equivalent of not having sloppy code. You wouldn't talk gibberish to a spider, so why talk gibberish to humans? After all, humans are your target audience. They're the reason you're optimizing to begin with. What good would it do to rank high on Google only to have SERP referrals quit your site in an instant when they see an unprofessional page loaded with grammatical errors. Note also that "bad neighbourhoods" are notorious for their poor grammar. For instance, experts say that spam email is easily identifiable by typos and poor grammar.
Are you trustworthy?
Here are a couple of proofreaders who might help you out: proofreaders and editors Better-Edit (owned by one of the first people to teach me about SEO, web entrepreneur Yaro Starak), Hyperlife.net, http://www.wordsru.com/, and whatever else you might find on Google for editing services. (Note the varied ways of obtaining backlinks and their quality, as determined by order listed and nofollow tag usage: relationships (first, nofollow not used), topping SERPs (second, nofollow used) and topping Adwords (third, nofollow used).)