I just did a BlogThis from Flickr to my blog (this post - http://www.tom-hanna.org/?p=801) and when it came through there was a "/" slash in front of every quote mark or apostrophe. The result was that the picture didn't show up, the links didn't work and I ended up with a bunch of extraneous slashes in the post. This hasn't happened before, though my last Flickr blog post was June 13 so it could have started anytime in between.
I did a test post to LiveJournal (http://www.livejournal.com/users/thanna/31132.html) and this didn't happen, so it looks like it's WordPress specific.
Is this related to the xmlrpc.php update?