Pushed the upgrade from Jetpack 1.7 to 1.8 this morning and the content of all blog posts disappeared from my home page. The "read more" links were still there, and clicking those showed the blog posts were still there. The home page was showing the title, featured image, and read more link, but no longer an excerpt.
Reverted the database and went back to Jetpack 1.7 for now. Using ClearLine theme.