It's amazing how many apps want access to my contacts that i had no idea was reading them.
A lot of people mistakenly think that Apple's vetting of apps for bugs somehow guarantees privacy as well.
It seems quite likely that a number of iOS apps have been collecting our contact info. Probably smaller ones, mostly, but
one blogger claimed the developers of popular apps do as well.
The majority of big name apps don't seem to grab all the contacts.
Article here about the ones that do and don't.
The whole trouble with blanket permissions like this is that they don't tell us what the app is really doing with the data. Sure, you want to give some apps access to contacts to help you, but not to transmit elsewhere. Perhaps there needs to be some kind of system log of transmissions that can be read by info-aware testers. Of course, if the data is encypted, that doesn't help.
As always, it boils down to how much you trust the app's source.