The title for one of my posts isn’t displaying, but it does for the rest of the posts. (It’s the second most recent post, entitled How Many Representatives Should We Have.) The title shows up on the specific page for that post, but not on the main page.
Blog url: http://rootsoftheequation.wordpress.com/
That’s what happens when you create an Aside (using the New Post button from the Admin bar) instead of a Post via Posts->Add new or the drop down menu from the admin bar.
You can edit it and if your theme supports post formats, you can change it on the right-hand side. If you theme does not, you’ll have to momentarily change themes to one that does, change it, then switch back.