I have an XMLRPC client that I wrote myself and it uses Markdown to preformat a post before submitting it to my blog. I'll note that I've been using it for a couple of years without this problem.
Just recently, it seems that the closing / character in img tags is being stripped. I haven't checked what happens to br or hr tags.
So, to be more clear, my client will send something like the following via XMLRPC:
<img alt="radar920AM" src="http://sahd.lamafam.org/wp-content/uploads/2013/03/wpid-imageShare.jpg" />
and what will show up in the actual source on the blog is:
<img alt="radar920AM" src="http://sahd.lamafam.org/wp-content/uploads/2013/03/wpid-imageShare.jpg">
Any ideas why this started happening?