I think it is PERFECTLY reasonable to have the same system for personal information that iOS has for accessing location.
"This app is requesting access to your ___________"
Allow or Deny?
that blank can be replaced with:
1. Address Book
2. Photos
3. Music Library
4. Location
5. Personal information (includes Notes, Reminders, email and SMS conversations, calendar events, etc.)
If you deny, it can be:
"this app requires you enter __________ or create an account to work, please manually enter your email address in the field below"
So, it's totally feasible. And you can have toggles for it, just like you do for location.
At least apple has an approval process for apps. On Android, this issue is totally rampant... It's disturbing to see it here, too.
EDIT: Regarding this: Apps that collect or transmit a users contact data without their prior permission are in violation of our guidelines, Apple spokesman Tom Neumayr told AllThingsD. Were working to make this even better for our customers, and as we have done with location services, any app wishing to access contact data will require explicit user approval in a future software release.
I'm GLAD. Good job, Apple. I fully expect this in 5.1