The whole reason, as far as I know, for mafia HAVING the mini-browser is so that it can display various thing that, for one reason or another, can't be properly passed to your main browser.
Edit to add:
That having been said, it's very possible that once everything is ironed out with combat macro support, there may be far less situations in which the mini-browser is required. But I dunno enough of the details to really say...
The whole reason, as far as I know, for mafia HAVING the mini-browser is so that it can display various thing that, for one reason or another, can't be properly passed to your main browser.
I thought the mini-browser was to handle the situation where for whatever reason you don't WANT to run a main browser application at all. With the mini-browser, mafia is self-contained and doesn't need the external application. (Not that I can think of many such situations that apply to me personally...)
Implemented or rejected? Currently, with the proper settings you get a link in the gCLI and you can click it to open in the Relay Browser. If that answers the request then Implemented. If the request was to automatically pop up the Relay Browser then that is actually a duplicate that I seem to recall has been rejected, primarily because popping up the browser requires a lot of special handling to work with all OSes.