Like a reference counter, it doesn't need to run collection cycles as it knows exactly when memory can be freed. Despite this, it handles circular structures just fine.
Apart from that, there's nothing special about it. The idea was absurdly low hanging fruit and that aspect might make it good LW post material. Assuming that it works as well as I think it does.
This is the fifth bimonthly What Are You Working On? thread. Previous threads are here. So here's the question:
What are you working on?
Here are some guidelines: