The FBI operation acted on "credible intelligence" that led to an investigation that resulted that began almost a year ago. Per reports from the press conference unveiling them, the slippers were recovered in July after a man contacted the insurer with information on the slippers themselves.
No one has actually been arrested or charged with the theft as of yet, however the slippers were insured for $1 million and would like fetch twice that if they were sold at auction. Only three other pairs of slippers from 'The Wizard Of Oz' are in existence - one is held by AMPAS, one held by the Smithsonian Institute and the third is held by a private collector.
The slippers - beyond their association with the movie itself - have no real value as such. The "rubies" are made up of sequins, whilst the bows of the shoes were made up of red glass beads, and they definitely don't bring you back to Kansas if you click them together three times.
Now that they've been recovered, the slippers will go back on display on the Judy Garland Museum, which also houses the largest collection of memorabilia from 'The Wizard Of Oz'.