In the User section, you can set the message you want to send to users. It allows you to use some variables that will be filled in when the message is actually sent.

User Variable Options:
!username, !site, !password, !uri, !uri_brief, !mailto, !date, !login_uri, !edit_uri, !login_url

Under trigger / Actions (module - off by default)... they are this:
%author ,%site_name, %username, %node_url, %node_type, %title, %teaser, %body,

Is this on purpose or just tow different paths for different modules?

Would it make sense to have a COMMON function/Filter that all modules can call to use in pulling in variables?

Just a thought for a future version.