First you need to enable Autofill in Settings->Safari
I currently have 'Use Contact info' off and 'Names and Passwords' on.
Then, I visited several sites that required names, passwords, etc.
Only SOME of them would spawn the confirmation panel that confirms if I want to save the password info for this site.
As long as I get that confirmation panel, no problems.
Only thing is, it doesn't happen for some sites. My bank's mobile site, for some reason, doesn't trigger the auto fill confirmation.
When I come back to the sites that I did confirm, they are already filled in without having to click the little 'Auto Fill' button in the Safari spawned keyboard.