This evening, I went to my "My Yahoo" page, a customizeable personal page you can populate with news wire feeds, RSS feeds, and other Yahoo content. And it had gone back in time.

Note how all all the stories are "one week ago". Normally this feed is somewhere between a few minutes to "one day" ago. And the "one week ago" is inaccurate since most of the stories are dated between February 9th to February 11th. The same went for the comics farther down the page (Feb 11th). The segments that related to offsite RSS feeds were current, but any feeds created/licensed by Yahoo were reaching WAAAAY back.
Wonder how long it will take to fix. Oh, it's fixed. Well, at least it lasted long enough to grab a picture.

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I've got the same problem and discovered it's nothing wrong with yahoo. Probably your browser served you some cached ajax request results.
If you are using IE you may want to click Tools -> Internet options -> Delete files ... in order to prevent such time traveling events
(To clear the cache on Mozilla goto Tools -> Clear private data...)
@Anusca,
Actually, I think not. It's happening again now, around the same time of night as last time.
I'm using Firefox, so first I just cleared the cache and quit, rebooting the browser to make sure nothing had been stored in RAM. I still got the "one week ago" and "two week ago" stories.
Then I chose "clear private data" and cleared everything but cookies and passwords and rebooted the browser before revisiting Yahoo. Still the same issue. Still the same issue with shift+reload too.