The weak Yen because of the aggressive monetary policies from the BOJ has boded well for Japanese exporters - sales and profits are up. I imagine Sony is benefiting from this. Plus they reported a profit recently (albeit most of it has to do with selling assets and not product growth). Either way, an increase is good and I hope the PS4 and their other products will do well over the years.
Playstation = The Beast from the East
Sony + Nintendo = WIN! PS3 + PSV + PS4 + Wii U + 3DS