Working with the folks at Valve, Puzzle Agent 2 is the first to use aggregated stats for Steam Community. This allows everyone to know important facts such as how much taxpayer dollars have been spend on all puzzle submissions (over $16 billion at time of post!).
Since release, the Windows version was keeping track of progress. It just took a while for the data to be exposed publicly. Now you can see how much money your wasting on incorrect submissions. :-D
You also have stats for your individual progress in the game, located at your personal Steam profile. You can even compare with other Steam users on their progress though these pages.
For anyone that wants XML version of their individual stats, you can use this URL as well:
You can find out more about Steam's Web API if you want to go crazy on stats.
If you have any questions or comments, fire away!
* Sadly the Mac version of Puzzle Agent 2's stats don't work, so play stats aren't contributing to global totals. :(
If/when other titles do Steamworks stats, this should be fixed.