[youtube]cEPQwDCtDuo[/youtube] [youtube]ZcN465oDLS[/youtube] [youtube]P8otwPxSlXc[/youtube] They mention it in one of the parts. It's basically rubbing in how good your micro is, so there is no gameplay effect or anything apart from different racial ranks displayed for the unit.
In the original SC units had ranks, but they had no purpose and they were always the same for each unit which was boring. Now, units rank up the more kills they get. It's still pointless though, but very nostalgic and fun anyways. Also it's logical now that you get ranks for kills etc..
It always annoyed me in SC how they had ranks and kills but they weren't tied to each-other. Another reason then to get SC2
In SC the Terran unit rankings were cool. It was more lore based I think. A marine on the ground would likely be a private but the head of a battlecruiser would more likely be a general or something. Sure nice for lore junkies but totally pointless for gameplay. I think the kill counter is enough. I see no need to have the rank tied to the kill counter. In single player that is. But in multiplayer sure do it, it's another fun but useless thing for the game .
In those videos they say that the rank is tied to the kill-counter as well as the name i.e. unit. It means a BattleCruiser won't start as a private, it'll likly go through ranks General, Adminral etc. What ranks will the SCV have I wonder? They're basically civilians, or the Probe, they're just a AI controlling a robot, hopefully something nerdy