In generating keys for a new hidden service, and the corresponding .onion address, does the tor client check for collision with existing .onion addresses? The process being so fast, I can't imagine how it could. Or instead, does it rely only on luck, in that the address space (280~1024) is so much greater than the number of published addresses?
Also, how many hidden service addresses have been published? Is it on the order of 107? As I recall, each of those ~106 Mevade slaves created a hidden service, and that's the largest known influx. Yes? I'm guessing that far more have been generated in seeking vanity addresses, but most have never been published.