I was a little frustrated to find that I'd been entering contacts by default into a group "All on my iPhone" so they weren't sync'ing to my other address books. And with iOS 5.0.1 it's not possible to move contacts between fro u ps. But that's for another rant.
I've started the rather boring manual process of re-entering my contacts so they end up in the group(s) I want, and I'm tidying up information at the same time. To make life a little easier I'm keeping the iPhone Contacts open, and adding entries to Contacts on the iPad.
However, I'm surprised to discover that some, not all, of the contacts I enter suddenly appear with the person's photo, even though I've not added it. I can't work out where they're coming from and so far there's no pattern I can see: it's not like I've ever used the iPad to login to Facebook, and not all the records with a photo are for people with a Twitter account.
What's going on? How does the iPad Contacts app get these photos? Are they all for people who have an iPhone or iPad?
Update: it looks like this is a feature of the iOS 5 integration with Twitter. See Apple's feature announcement about Twitter at Contacts applies your friends’ Twitter usernames and profile pictures.