I have the requirement of running the Wordpress admin over https. We use a cdn to deliver cached content for the site but the cdn cannot accept secure traffic (only one SSL cert
If you're using Apache to serve over SSL, look into mod_proxy.
Using it you can transparently redirect all requests from https://secure.mysite.com/blog/ to http://www.mysite.com/blog/.
https://secure.mysite.com/blog/
http://www.mysite.com/blog/