Ack, that still doesn't prevent slides from going online. Just include your speaker notes. Problem solved. More work of course, but problem solved. Here's a fantastic example.
http://www.valvesoftware.com/publications/2012/GDC2012_Ruski...
http://www.valvesoftware.com/publications/2012/GDC2012_Ruski...
Did you look at the link I posted? It's a far more enjoyable, engrossing, and informative format than the equivalent multi-post blog series.
..edit: I like Markdown too much.