How did you get to have "Journeyman(4)" on your membership status, Mumble?
It used to be that all of SD's seperate forum sites were pretty much independent. They did have a common registration and login but otherwise they grew up as independent sites. About a year ago they put in major forum upgrades that tried to make all of these sites more consistent (that's when a lot of the forum "sharing" came into play).
Anyway it used to be that the GalCiv2 site had an independent forum ranking system along with forum stats associated with the metaverse. Other sites, most notably WinCustomize, also had a forum ranking system in place although I don't believe that they had a similar forum stats function. On WinCustomize the forum rank was used to determine whether folks could directly submit skins or whether they needed to have them "approved" before they could be downloaded by others. I'm not totally sure of the exact details but at least on WC the individual forum ranks had a functional meaning and use.
On the GalCiv2 site they used to have ranks that were quasi game related. There really wasn't all that much that forum ranks allowed you to do other than at the rank of Diplomat and above you had access to a special area. This area is still in existence today although it hasn't been used in a long time. You can actually see remnants of it yourself by going to http://www.galciv2.com/Council/Forums.aspx.
Anyway the GalCiv2 forum ranks used to be Citizen, Veteran, Diplomat, Ambassador, Governor, Avatar although there may be another rank or two between Governor and Avatar. These ranks may also have to do with the early system of users being moderators. Kryo came up through this system until he simply became a SD employee and he could certainly add more detail to all of this. I used to be an Ambassador which correlates to the Journeyman (4) rank.
As far as how one received rank I think it was essentially assigned from above, possibly from folks like Brad and Cari or more likely from Kryo with perhaps Brad/Cari/Zoomba's approval. I got most of my rank from the days of the Metaverse Council, however these days a new unified system is in place that is common to all sites although interestingly enough your forum rank (like karma) does not translate from one site to the next. Basically they still use forum rank for it's original purpose on WC but elsewhere it hardly makes any sense. They only difference that I can tell is that when I give karma it defaults to giving 4 points although I can change that from 1 point up to my forum rank of 4. Prior to the forum upgrades Neilo had been promoted to veteran which translates to Apprentice (2) and he can give 2 points of karma.
Other than giving karma there seems to be no funtional use for forum ranks anymore.