Expect Gawker Media’s latest advertising innovation to draw criticism, if not blood, when it sees daylight today. The blogging empire is temporarily welcoming a new site into its fold that’s written and paid for by HBO to promote the network’s noir vampire drama, True Blood. And the word “advertisement” won’t appear anywhere in the project’s vicinity.

Entries from the blog, BloodCopy, will appear as cross-posts in the mix of Gawker Media’s eight verticals, which include Gizmodo, Kotaku, and the flagship. They’ll be set off by a border and labeled as BloodCopy posts but otherwise indistinguishable from editorial content — except that the blog is written by an undead, bloodsucking ghoul.

“With vampires, we thought we could be a little looser with the disclosure and create some disbelief,” Chris Batty, Gawker’s vice president of sales and marketing, told me yesterday, dismissing critics of the advertorial as “humorless.” He also made a bold prediction that surprised me so much I made sure to confirm I’d heard correctly: “If we’re around in three or four years,” Batty said, “the majority of our advertising revenue will be in sponsored posts like this.”

Now, I’ll let others hash out the very-legitimate ethical questions this all raises. Gawker managing editor Gabriel Snyder, echoing a 2007 incident, has already denounced the ad sale: “What’s advertising should be called advertising and what’s edit should be called edit. It hurts both to blur the distinction.” But that’s an easy angle compared to what’s also going on here, which is the fruition of a long-held belief that advertising should act more like content.

“We’d like people to look at what we’re doing with HBO and see that it’s possible for advertising to tell a story,” Batty said, telling me a story of sorts. “True Blood is a narrative, so its campaign should be a narrative, and blogs are the best forum for that, we think.” He also threw around terms like “in-narrative exercise” and “marketing paradigm,” but the upshot is that it makes much more sense for advertisers to deliver messages where readers expect to receive them — within a site’s stream of content — rather than shoved to the side in a display ad.

A good example is this Lifehacker post, written and paid for by paper-shredding purveyor Fellowes, which ran as part of a series in March. In that instance, as you can see below, the content was labeled both “advertisement” and “sponsored post.”

Batty compared the HBO campaign, which starts today at noon, to custom publishing in the magazine industry. “We’ve got rack space, basically, to sell across the Gawker titles,” he said. That was a familiar comparison: Gawker chief Nick Denton has often likened his company’s advertising to glossy spreads in high-end magazines. (Denton, incidentally, passed along my request for an interview to Batty.)

BloodCopy will live amid the Gawker Media family for three weeks, until the premiere of True Blood‘s second season. The campaign “costs a lot more” than Gawker’s already-expensive site takeovers, Batty said. We’ll see whether there’s also any cost to Gawker’s editorial integrity.