No real central authority deciding. If an idea looks good (meaning it's well thought out, solves some sort of problem or adds quality of life, etc) though then it'll probably get posted about in the dev board by smods/admins/gms/CMs/msquad for further discussion and fleshing out of details and how it should be implemented. Quite a few ideas make it that far but unfortunately there isn't a whole lot of manpower available to do development.

I support this idea and I'd propose even an extra tag so we'd have:
[Elevated] - to signify that the idea has been taken to the devs
[Implemented] - to signify that an idea has been implemented

Of course as I said above, something being elevated is definitely not a guarantee that it will be implemented. Great ideas are often posted but are just too complex to get done with the dev capabilities we have. If that's what you mean by 'expose them' then yea I've never shied away from being a bit sad about the lack of dev power we have. But I'm all for transparency and I see no reason not to do this so I'll make a memo to the rest of the staff so they know too.