This is currently happening right now and the speed of the regathering is increasing.  These Jews are coming from the four corners of the Earth as predicted in Isaiah and Jeremiah.  As of January 2nd, 2015 was the greatest year for Jews returning to Israel with a total of 28,000 arriving that year.  The previous high was in 2014 with 26,500, which was up from 20,000 in 2013.  And despite the troubles happening in the middle east, 2016 looks to be the third year in a row that Israel has broken the record for the total number of Jews seeking Aliya in Israel!  Praise God, the Jews are returning home!

UPDATE (2019-11-1):  I realize that not all the Jews are back home, and most won't return until AFTER Ezekiel 38 plays out, however we have reached the tipping point where there are more Jews in Israel than in the world.  So, to me, that's good enough to mark this as fulfilled, as I don't think we need to see a 100% return to consider this as fulfilled.  Again, not completed, but rather merely fulfilled.