I was asking about McCain's VP Pick (Palin from Alaska) and I suggested that they may have chosen her to take her out of politics, rather than to promote her. That initial post was quickly moderated up to "+4, interesting". Then just as quickly came three "overrated" tags, putting it at "+1, interesting". My posts start at +2, due to my karma bonus, so at that point my post had been down-modded to a score below where it started. Later someone applied "insightful", scoring it as "+2, interesting". For this case, I'll admit that what I said was controversial and based on some assumptions that people clearly did not agree with. However I would still say it would be more appropriate for someone to post a response than use the cowardly "overrated" tag.
In what I would expect to be a far less controversial post, I questioned whether the iPhone / Flash incompatibility should be blamed on Apple or Adobe in the topic related to the British Government claims regarding the iPhone incompatibility. That comment was moderated all the way up to "+5, insightful", before being knocked down to "+3, insightful" - again by "overrated" tags. Someone later tagged it "interesting", scoring it back to "+4, insightful".
Yet another example of bad use of the "overrated" tag - this time on a non-moderated post - was in the discussion of Terror Watchlist Crippled by Technical Flaws, where I replied to a post and suggested that our poorly-maintained watch list was well known to be poorly maintained around the world. This was first moderated down "flamebait", then moderated back up "funny", ending up "+2, funny". Yes, this wasn't a misused "overrated" tag, but the flamebait was also not reasonable, and possibly missed in meta-moderation as well.
And finally, the first post of mine to recently recieve a non-sensical "overrated" moderation. Under the recent poll How Much Olympic Coverage Have You Watched? I commented on how the excessive media coverage had made this into the Michael Phelps Olympics. Two people responded in agreement that swimming has a disproportionate number fo medals for an Olympic discipline. But yet one person attacked with the "overrated" tag, when no moderation had been applied to that comment.
In summary, partisan moderation is no surprise. It was inevitable. But the "overrated" tag is cowardly. I have never seen one come up in meta-moderation, which makes them pretty bullet-proof for people to down-moderate postings that they don't like (or from people they don't like). Overrated needs to go. It should be replaced with something that actually allows someone with moderator points to say something about why they want to down-moderate a post.