In Ken Goe's article he said theres an unverified rumor going around that it is a stress fracture in the back...i sincerely hope not as this is a really alarming injury for a couple reasons.
Other than the obvious answer of any injury to the spinal column being very serious, what are your other reasons? I'm interested to hear your speculation.
btw, that picture in the article is quite simply, the worst image of Alex Kosinski I have ever seen. She usually looks better than that at the end of a very tough race when she is in pain. Teh Oregon athletic department photographer who took that should be fired. ;)