I came across this great post by Amanda Luker of the Drupal consulting firm Advomatic: Designing for Drupal: Dos and Don'ts. It describes some key principles that designers can use to ensure their designs are reasonably build-able in Drupal: "reuse, flexibility and standardization."
Okay, maybe not world domination. But at least some serious progress toward some really usable, community-developed technology. That's a big deal. I feel like Drupal and WordPress are hitting their stride more and more. It's getting easier to build sites on a budget that orgs can mostly manage and update themselves. I've been building proprietary and open source CMS sites for nonprofits for over a decade, and I feel like right now, CMS technology is particularly accessible.