We are working on a migration path that will switch people over to the HTML versions (unless they don't want it). Are you one of those people? If so ping me directly - jared at scribd.
I was wondering about this too. I often get document conversion errors (using the JavaScript API), especially with UTF-8 documents. Think HTML5 will help?
Honestly, I'm not sure. Send me your Scribd username and I'll take a look.