But the relationship between the two, which Twitter has been actively trying to promote in the last nine months or so, is a funky one: Sometimes Twitter gets excited about TV shows that lots of people don’t care about. And sometimes TV’s most popular shows aren’t nearly as popular on the social messaging service.

You can see this illustrated quite effectively via data from SocialGuide, a start-up that tracks who’s saying what on the Web about live TV. SocialGuide wants to track TV commentary on all of the social media platforms, but right now it has the best bead on Twitter, because it has access to the service’s data “firehose.”

So while the chart below, which looks at TV shows that aired during the last week of May “sweeps,” technically encompasses more than Twitter data — there’s some Facebook commentary included there, for instance — it’s best to look at it as a Twitter proxy for now:

Notice that some of the most popular shows on TV are also a big deal on Twitter: American Idol, Glee, and some of the NBA playoff games map very closely on the two rankings.

But in other cases, there’s a big disparity.

For instance, there’s a slew of reality shows — “Mob Wives,” “America’s Best Dance Crew,” “Khloe & Lamar,” etc., that don’t crack the Nielsen top 100 for the week, but all place very highly on SocialGuide’s chart. Meanwhile, some of TV’s most popular shows, like “NCIS” and “Modern Family,” show up much further down SocialGuide’s rankings.

(If you’re interested in methodology, here’s a brief version: SocialGuide is only tracking commentary made while the shows are airing. But it’s attempting to track both explicit “check-ins” — either made using Twitter hashtags or via services like GetGlue — and implicit ones, when users refer to the show by name, etc.)

So what does that tell us? Hard to say. It’s tempting to make demographic links on some of these shows — for instance, surveys show that Twitter has a disproportionately large African-American user base, and perhaps that skews the ratings for shows like “Love & HipHop.”

But the data is pretty scattered, so I’d be wary of that: Anyone want to suggest why “Extreme Couponing” does well on Twitter? Also, is “Extreme Couponing” what I think it is?

In any case, the dream scenario for Twitter’s sales and marketing team (hi, Adam!) would be data that shows increasing Twitter popularity reflected in a show’s ratings. SocialGuide is just starting to publish this data, so it will be worth watching in the months to come.

Recently, Foursquare was selected for an “award,” as part of an advertising campaign for USA Networks, whose motto is “Characters Welcome.”

On its Web site, “USA Network’s Character Approved: Honoring 12 Cultural Trailblazers” is described as “innovators in their field who influence our opinions, our style, and our view of the world.”

Now, a commercial featuring co-founders Dennis Crowley and Naveen Selvadurai is in heavy rotation on the cable television channel–what can BoomTown say, except, “NCIS” rocks, and thus, I have had to endure the ad 67 times so far!

In fact, it’s actually kind of sweet and awkward, as the pair try to explain the social geo-location service to the masses.

Enjoy:

I’ll confess up front that I don’t know, and the two companies themselves aren’t being helpful in explaining the kerfuffle. But here’s the best guess from online video folks who know both companies: Hulu isn’t pumped up about supplying its content to a competitor–especially since CBS isn’t supplying its content to Hulu.

For what it’s worth, Hulu, the joint venture between News Corp.’s (NWS) Fox and GE’s (GE) NBC, offers up this statement: “Hulu has contractual rights with regards to our relationship with TV.com and we are exercising those rights. Out of respect for their confidentiality, we will not disclose our discussions.” CBS offers up a more concise “no comment.” (News Corp. is the owner of Dow Jones, which owns this Web site.)

[UPDATE: CBS weighs in with a saber rattling statement on Thursday afternoon: “CBS Interactive is well within its rights to stream Hulu video content on TV.com under its agreement with Hulu. We are evaluating our next steps at this time.” ]

The background: CNET, which CBS (CBS) purchased last summer, has owned the TV.com domain for several years. This year, CBS relaunched the site as a Hulu-like video portal. Included in the launch was video from Hulu itself, which syndicates its stuff to dozens of sites, including MySpace, Time Warner’s (TWX) AOL, and Sling.com.

The wrinkle: Hulu’s distribution deal was inked with CNET when the company wasn’t owned by CBS. And CBS doesn’t provide its video to Hulu. You can connect the dots here, and that’s what several folks I’ve talked to today are doing. If either one of the companies decides to become more expansive, I’ll update when appropriate.

In the meantime, here’s a clip of “NCIS,” a CBS show you can’t get on Hulu:

And a clip from last weekend’s “Saturday Night Live,” an NBC show you can no longer see on TV.com: