First, congratulations to Bergoglio.
I don't have many thoughts on this (perhaps Evan has more), except insofar as there was a real prospect of a pope from the developing world, and that introduces prospects for discussions of social justice, liberation theology, the church and the left, and political economy generally.
From that angle, this is an interesting choice. Argentina is not exactly a developing country, after all. It's part of the G-20 and is generally a notable economy with high ratings on various development indices, despite struggles with inflation. So in that sense, it was sort of an "outside of Europe but not as far as the developing world" kind of choice. In the same vein, Bergoglio apparently distances himself from liberation theology and even from pronouncements on social justice generally.
Like I said, this is just a quick reaction from my corner of the world working off of googling.
Any other thoughts on the selection are welcome.
UPDATE: Others have a different take. I was just Wikipediaing.