Saurik has revealed that the release of the Corona jailbreak for A5 devices has led to nearly one million newly jailbroken iPhone 4S and iPad 2 devices, in just 3 days.
So, @MuscleNerd's 205k number was just the number of on-Cydia iPhone 4S's; I believe that is now 494k. iPad 2 5.0.1 adds an additional 463k.
When Cydia is launched for the first time, it contacts the Cydia server, in part to see which SHSH blobs are available for it. This 957k number should be an accurate report of the total number of A5 devices jailbroken as of Monday afternoon. (Note: the number doesn't include A4 devices or lower).
The iPhone Dev-Team has posted the exact numbers:
? 491,325 new iPhone4,1 devices
? 308,967 new iPad2 devices
? 152,940 previously jailbroken (at 4.x) iPad2 devices
Total: 953,232 new A5 jailbreaks in a little over 3 days
The release of Corona for A5 devices marks the first time a jailbreak has been available for the iPhone 4S. To find instructions on how to jailbreak your device using the new Absinthe utility you can follow our handy Jailbreak Wizard.
iClarified - Apple News - Nearly 1,000,000 Newly Jailbroken Devices in Just 3 Days