This is all because of the Lumia 520, which is really driving Nokia's sales. There is a good space at the low end of the smartphone market and with people moving towards prepaid or no-contract in the US, a cheap off contract smartphone like the 520 is a really winner.

This is also good because Nokia is like 80+% of Windows Phone sales, so that means Windows Phone is creeping upward against Android (for better or worse)