Gee I'm glad when I stimulate a discussion about something that I find interesting. I too have learnt a little more myself about these things too.

The Hack that is out for the Canon 300D Rebel activates features that have been diabled by Canon as the guts of the Rebel's electronics is essentially very very close to that of the Canon 10D. There are many people using the Hack and using it very successfully. Not that I am recommending it, but bought up the mirror lock for discussion purposes.