Not much more information that what is in the headline, but The New York Times reports this morning:
NYTimesI see now HoundDog has an earlier diary up. I swear I looked. Sorry for the duplication.
WASHINGTON — The State Department said Saturday that Secretary of State Hillary Rodham Clinton, who skipped an overseas trip this past week because of a stomach virus, had suffered a concussion after fainting.
The agency said that she was recovering at home and was being monitored by doctors.
The department said Mrs. Clinton was dehydrated because of the virus and that she fainted, causing the concussion. No further details were immediately available.
11:17 AM PT: I'm going to leave this up and use it to refer people to the discussion in HoundDog's diary. It looks like a few people missed it as I did.