Yes, Ipstenu is right. The plugin was one of my first ventures into the PHP world and contains some serious security holes -- especially if you're allowing users to edit their own posts.
Rather than attempt to fix something that was a bad idea from the start :D -- I've decided to pull uCan Post off the shelf permanently.
I've learned a lot since and will be releasing a new Blog Post submission plugin in the future which will be far more secure and feature rich. It's about 75% completed at this time. I don't have a name for it yet.