You might want to ask whether users have installed any game associated with OpenFeint. Some examples are listed on their Wikipedia page: http://en.wikipedia.org/wiki/OpenFeint.
Heh, I've been compiling the same list as you already did. My results look a lot like yours.
What do you mean that it is "very dangerous"?
As I posted in another thread... I wonder if it is significant that so many of the UDIDs are known to OpenFeint. If you took a random sample of UDIDs, how many would OpenFeint have data on?
I've been fetching results from the openfeint api for a bunch of the UDID's. I'm not sure, but it may be significant that so many of the UDIDs get a result from the API. Shouldn't openfeint only know about the UDID if the user has played some game in their network? And wouldn't we expect that to be a distinct minority of the total population of all ipad/iphone owners?
