UPDATE: Bit Tech reports 2K Games has sacked The Redner Group over the incident:
2K has since stopped doing business with The Redner Group and said, via its own Twitter feed, that it doesn't endorse or condone the comments.
'We maintain a mutually respectful relationship with the press and will continue to do so. We don't condone @The RednerGroup's actions at all,' said 2K.
Register Hardware reports The Redner Group, the PR team behind the US launch of Duke Nukem Forever, threatened on Twitter that reviewers who bashed the game would be blacklisted.
One staffer posted threats on the agency's official Twitter page stating the team will decide "who gets games next time" based on the venom in a reviewer's piece.
The Tweet has now been removed, replaced by a grovelling apology and the promise that individual sorry letters will be sent out to worried reviewers.
According to ArsTechnica - who managed to grab a screenshot before the original Tweet was removed - blacklisting is a common thing in the games world, and has been for years, but the activity is rarely made public like this.