The iPhone Dev team just released numbers for the Absinthe A5 jailbreak. According to the site, 953,232 new jailbreaks were recorded. That's a whole lotta hacking.
Absinthe A5 was released Friday months after A5-powered iPhone 4S and iPad 2 first hit the market. The CPU was actually the main reason why the hack was a bit more difficult to pull off than previous jailbreaks. And if you're worried that spying tools are the reason why the Dev Team knows how many devices have been jailbroken, you can rest assured that's not the case.
The reason these number can be so precise is that one of the housekeeping activities that happens when you launch Cydia is a query to @saurik's server for the list of available SHSH blobs. (Even if you have none on file, the query is still made).