Is it possible and if so what are the steps necessary to package (or build) a Mac OS X application and code-sign it so that it can be downloaded with Safari and automatically launch?

... possibly after the user responds to some sort of dialog explaining that it is a signed application and the publisher has been verified. An example of the user experience I am trying to create is "installing Google Chrome for the first time on Windows", which is a 3-click, less-than-a-minute process. For the concerned among you: I am not trying to create a drive-by download. I am fine with some sort of intermittent user step approving the download. I just want to make the installation as quick and painless as possible and not require the user drag the app from a mounted DMG into the application folder. This may not 100% jibe with established Mac OS X user interaction guidelines, but it would work better for the not-power users.

I only need the high-level steps or pointers to resources ... my google-fu was weak on this one.