I'm sure it has already been asked. It's just that every couple of months, facebook changes their APIs and the question becomes new...
What is the current way?
(I got the user to accept the extended permission thingy).
The FB help, claims I have to use getInfo().contact_email which doesn't exist in the .net toolkit.
"email" is the field you want, as listed here. It contains the user's proxied e-mail address (@facebook.com) or their genuine address, or is blank if they haven't given your application permission to mail them.
I haven't looked at the .Net toolkit for quite some time, but if that field isn't present then the workaround that doesn't involve delving into it and recompiling would be to do an fql query on the user table.