Apparently it was a busy weekend for the FBI. The agency was all set to face off with Apple tomorrow over the unlocking of shooter Syed Farook's phone. But it now says that an "outside party" approached them on Sunday with a way to possibly unlock the phone. TLDR: They might not need Apple to unlock it any more.
First spotted by Nate Cardozo, a lawyer for the Electronic Frontier Foundation, it looks like the FBI is asking for a delay so that they can explore this potentially "viable method".
On Sunday, March 20, 2016, an outside party demonstrated to the FBI a possible method for unlocking Farook's iPhone. Testing is required to determine whether it is a viable method that will not compromise data on Farook's iPhone. If the method is viable, it should eliminate the need for the assistance from Apple Inc. ("Apple") set forth in the All Writs Act Order in this case.
It would appear that the FBI isn't entirely giving up its option to make Apple unlock the phone. But they're asking for more time to see if this unnamed "outside party" has a method that works.
Interestingly, the motion says that the international attention that the case has received means they're getting offers all the time from people who think they can crack the phone without Apple's help:
Specifically, since recovering Farook's iPhone on December 3, 2015, the FBI has continued to research methods to gain access to the data stored on it. The FBI did not cease its efforts after this litigation began. As the FBI continued to conduct its own research, and as a result of the worldwide publicity and attention on this case, others outside the U.S. government have continued to contact the U.S. government offering avenues of possible research.
Emphasis mine. I sincerely wonder if we'll eventually learn who cracked the phone, should this all work out for the FBI.