I was just checking the OpenSocial 0.8 JavaScript API at:
http://wiki.opensocial.org/index.php?title=Requesting_Data_in_OpenSocial#Fetching_a_group_of_people
And found this line about retrieving data by ID:
"This section introduces the fetch people request, which is commonly
used to retrieve the friends of the current viewer or app owner but can
also retrieve specific individuals if their OpenSocial IDs are known..."
In my application, I do know the OpenSocial IDs of all the other app users. However, it is not clear if these OpenSocial IDs must belong to either the friend or the owner in order to access them.
Still perplexed...