Schneider's concern here is to find out about the care that is put into a site, which she considers to be a good indication of its quality. To help assess this, he LII investigates whether a web site's external links are functioning properly. She also mentions something that seasoned SEOs will already know: "Beware of student project web sites and personal web pages with many, many links!" Links from poor quality website and websites with hundreds of links in which your own gets lost aren’t all that valuable.
Luckily for SEOs, this particular trend in Google's development is not a major one, meaning that little additional work will be required to adapt to it. (Unless you're doing SEO on contract for others, in which case this small augmentation in workload is a dissapointment.)
The reason is that some of this is already integrated within Google. For instance, Google engineer Matt Cutts' blog, in discussing Google's recent Big Daddy update, considers the cases of some websites that suddenly found much fewer of their websites indexed. He suggests that the cause of their woes was external linking to unrelated websites. This is a quality issue, but it reflects the idea that Google's on-site considerations include external links.
The trend in SEO is therefore, in the main, a continuation of previous trends. As Schneider said, the care that is put into a website is important.
Proper coding in link structures (and of course linking to what the anchor text actually describes) should be paid specific attention to.
Check your links on a regular (once every two weeks feels sufficient to me) basis in case sites have moved, and if they have, update your links.
As always, avoid sneaky redirects.
When building a network of backlinks, aim to gain them from pages with few outgoing links, and find out if their current external links are in good condition (and if not, let them know – you'll both win).