I found a post which had no title when working on my rss display on the hcmc site.
http://hcmc.uvic.ca/blogs/index.php?blog=28&p=901&more=1&c=1&tb=1&pb=1
It looks odd in that context, and I'm sure similar title-less posts will look odd in other contexts within the blog, so should trap for an empty or nothing-but-whitespace value in the title field when the user tried to submit a post.