Look ye Jetpack users on Self-hosted WordPress blogs (my emboldening):
WordPress bloggers can embed Tweets directly into their posts by simply copying the Tweet URL or using a familiar shortcode. Once published, WordPress instantly turns that URL or shortcode into an embedded Tweet. WordPress.com and WordPress VIP blogs have this functionality immediately, and Jetpack users will get it with their next update. For more news about WordPress and Twitter, check out founder, Matt Mullenweg’s blog post.