To play devil's advocate for a second: could it have anything to do with the fact that bitcoincharts is owned by Tibanne Co., Ltd., the company that runs mtgox? Maybe give people a little incentive to keep trading on mtgox... I mean, who wants to trade on an exchange whose data isn't even properly displayed. Then again, it's not as if mtgox has anything to fear from bitstamp, their position as the dominant exchange is as stable as ever. Oh, wait.
What makes you think Tibanne owns them? They host the site, but I don't think they own them.
You're right, I have no idea who *owns* bitcoincharts. I do know that the registrar of the domain is Tibanne according to whois
So it is hosted by Mark Karples hosting company.... Like a hundred other Bitcoin related sites.