Nielsen and Twitter just announced a deal for something called the Nielsen Twitter TV Rating, which they’re hoping to turn into the standard metric for measuring the conversation that a TV show spurs on Twitter.

The companies say they’re planning to make the rating available commercially in the fall of 2013. The new Twitter ratings are supposed to complement Nielsen’s existing TV ratings, and will be built on top of the SocialGuide platform offered by NM Incite. (NM Incite is a joint venture between Nielsen and McKinsey, and it announced the acquisition of SocialGuide last month.)

In a post on the Twitter blog, the company’s head of media Chloe Sladden said Twitter’s TV partners have been asking for “one common benchmark from which to measure the engagement of their programming.” And according to the press release, the new rating will measure “the total audience for social TV activity – both those participating in the conversation and those who were exposed to the activity – providing the precise size of the audience and effect of social TV to TV programming.”

It doesn’t seem like either company is releasing too many details about the new rating and what it will be measuring yet. Here at TechCrunch, Gregory Ferenstein has written skeptically about the numbers that social media platforms use to tout the impact they can have (he was talking specifically about politics, but was also making a broader point).

This is an area that startups have explored as well (Bluefin Labs comes to mind), so it will be interesting to see how they respond now that Twitter is partnering to expand its own measurement options.

In the release, Steve Hasker, president of global media products and advertiser solutions at Nielsen, points to the opportunity that the Nielsen Twitter TV Rating could have on measuring ad campaigns that include both traditional TV advertising and Twitter:

Earlier this year, Twitter and Nielsen also partnered to use Twitter surveys to measure the impact of brand advertising campaigns.