As odd as it seems now, when Apple first launched their iOS Push Notification services, they had absolutely no way to corral and manage them. For that, Boxcar was a godsend.
I had written about Boxcar a number of times over the past couple of years as it became a must-have app on my phone, and later, my iPad and the Mac as well. Even after Apple entered the space with their own Notification Center (now baked into OS X Mountain Lion as well), Boxcar was useful because it allowed apps and services that might not otherwise do Push Notifications, to easily do them. And it allowed users to create their own.
It appears that work will continue under Kwaga, as they’re not shutting the service down, but investing more into it. Congrats to both teams.