That factoid comes via Web-tracking service comScore (SCOR), which says the two sites accounted for 17.4 percent of the display ads in the U.S. market in July.

News Corp.’s (NWS) MySpace, in the midst of a turnaround effort, has a slight lead over Facebook–9.2 percent of the market versus 8.2 percent. That makes sense since MySpace has always been aggressive about loading up with ads, while Facebook has been fairly reticent, much to the dismay of the “when are you going to monetize?” crowd. (Click table to enlarge.)

That’s something you knew intuitively, of course. But interesting to see it in graphic form.

Another data point you already knew, but may still find worthwhile to see in black and white: Just how small the scraps are for the rest of much of the social network ad world. By comScore’s count, the next eight-biggest social networks command a collective 1.4 percent of the market. (By the way, ever heard of MocoSpace.com before? Do you know anyone who claims to be a user?)

Remember that we’re just talking about overall impressions, not dollars. And ad impressions on social networks are famously cheap, so this stat only tells part of the story. But it’s an important part. It illustrates the potential that the services have, even if they haven’t capitalized on it (not that they haven’t tried).

Meanwhile, here’s a bonus table from comScore laying out the top advertisers on social networks. No surprise to see the likes of AT&T (T) and Sprint (S) here. But perhaps it’s noteworthy that Verizon (VZ), the strongest U.S. telco, spends the least on social media impressions. Meanwhile, social network app makers/services like Zynga are spending heavily.

(News Corp. owns Dow Jones, which owns this Web site.)

Ever worry that the ever-increasing barrage of status updates from Facebook, Twitter and every other real-time, hey-look-what-I’m-doing and look-what-happened-just-this-very-second service may be outstripping your brain’s capacity to process them?

You’re probably right, says a new study from a University of Southern California neuroscience group. Physorg.com:

“‘For some kinds of thought, especially moral decision-making about other people’s social and psychological situations, we need to allow for adequate time and reflection,’ said first author Mary Helen Immordino-Yang.

‘Humans can sort information very quickly and can respond in fractions of seconds to signs of physical pain in others.

Admiration and compassion–two of the social emotions that define humanity–take much longer….’”

Too many words? Want to cut to the chase? OK:

“The study raises questions about the emotional cost–particularly for the developing brain–of heavy reliance on a rapid stream of news snippets obtained through television, online feeds or social networks such as Twitter.

‘If things are happening too fast, you may not ever fully experience emotions about other people’s psychological states and that would have implications for your morality,’ Immordino-Yang said.”

Blah blah blah. I’d write more, but I just caught wind (heh) of this story about a chair that Tweets its user’s flatulence. Gotta go!

I still haven’t heard back from FriendFinder Networks or Andrew Conru, who appears to be the founder who sold his company his car in 2006. But MediaMemo readers tell me the car in question is a Ferrari 360 Modena, similar to this model on sale, via eBay (EBAY), at Excel Auto of Boca Raton, Fla. (click image to enlarge):

I thought this car might actually be the same one that FriendFinder owns, since it says the car in question is being held for sale, and because FriendFinder is also based in Boca Raton. But a manager at Excel tells me that’s not the case.

Disclaimer: I need to note that while I appreciate the tips MediaMemo readers have passed along, they remain unconfirmed. So it could be that FriendFinder owns a different kind of car that it purchased for $125,000 two years ago and now values at $95,000.

The bigger question: Why would FriendFinder buy a Ferrari (or any other kind of car) from its founder a couple of years ago? And what has it done with it since? Did employees of the month get to take it for a spin? Has it been mothballed? Did it sit parked in front of the company’s HQ as an incentive to work harder and longer?

(UPDATE: A partial answer — the car was supposed to have been given away as a contest prize.)

As always, if you’ve got thoughts on the matter, you can comment below, or reach me directly at peter@allthingsd.com. If you want to be completely anonymous, you can use the blind tip box here.

No matter. If it works, it’s going to make a lot of people happy. So who’s biting?

Well, Ben & Jerry’s, for one. The groovy ice cream maker–owned by less-groovy conglomerate Unilever (UN), but who’s counting?–is one of Facebook’s favorite examples of a brand that has used the site to do more than just generate click-throughs. Last spring, Facebook COO Sheryl Sandberg talked up a free cone promotion that drove hundreds of thousands of people to the chain’s stores.

So if it worked once, why not do it again? The two are running a new version of the promotion today, with Ben & Jerry’s sponsoring Facebook’s election page, which features a Google (GOOG) map that tells voters both where to vote and where the nearest B&J outlet is. Pretty clever, really.

Also clever: Facebook’s running total of users who’ve declared that they’ve voted in today’s election, which stands at about 2.06 million as I type this. Since this is a self-reported number and one that doesn’t come tethered to any other demographic information, it’s statistically useless.

But that won’t stop endless commentators from using the stat tonight and in the days to come as an indicator of what the “youth vote” did or didn’t do today. Which, of course, will drive more traffic back to Facebook–and Ben & Jerry’s.