Posterous has added Facebook Like buttons to all of its standard themes today. Click a Posterous Like button and the blog it's on is "shared" to FacebookBuilding on Facebook's OpenGraph API,
For designers, inserting a "like" tag in a theme and adjusting the href attribute to whichever page they want a user to Like will create a Facebook-facing button for that theme.
Facebook's recent changes include proliferating the number of pages in its system by transforming profile fields and interest areas into discrete pages and allowing app developers to retain user data for a longer period of time and, of course, the out-of-the-box Like function.
Facebook's size, and the likely increase in its web gravity, is no doubt inspiring developers from horizon to horizon to include Like buttons and like features in their products.
Expect a significant upturn in Jack Horner references.