Forum OpenACS Development: Re: Adding email alerts to general comments
In this case it seems that you should be investigating ways to integrate notifications into general comments. Notifications gives the user a single place to control the alerts they get from an OpenACS site. There is also support for SMS alerts floating around (not sure that will go into our standard code because there's not one standard way to do it as there is with e-mail), and probably there will be support for other types of alerts added by folks in the future.
The notifications paradigm is that the user controls what they get, rather than (say) the author of a comment. Though of course there's nothing that stops a package from allowing its admins to add notifications for a user or to even add notifications silently (the homework package sets up automatic notifications to tell a student when a professor's comments have been uploaded, for instance).