Update (12:58 a.m. EDT): Fight's off, says Dan Rafael of ESPN.com. Rafael doesn't get ahead of himself when reporting stories, so that makes it pretty much a done deal.
Here's a photo of Julio Cesar Chavez Jr's injured hand, from his Twitter account:
Here's another angle:
Apparently this happened when Chavez got his hand caught in a ceiling fan, and Lou DiBella says he's been informed that the September 17 fight with Ronald Hearns is off. Chavez appears to be trying to "put on a brave face" and isn't confirming that he's out of that fight yet, and also says his weight is fine, but it appears all but official that the fight is definitely not going to happen, be it from this hand injury (there is an injury in those photos) or from the more widely-held belief that Chavez isn't in good enough shape, and doesn't have Freddie Roach and Alex Ariza training him for the fight. With no Roach, no Ariza, no Top Rank, no Zanfer, this fight has been a questionable mess from the get-go.
All that's left to find out is whether or not the fight is off, but all signs are pointing to that being the case. It wouldn't be the first time that Chavez has pulled out of a fight.