Remember iPhoto is a series of interlinked databases, so permissions are different than ordinary files and folders. That's why there is an option to repair the permissions with iPhoto. I would note that many people with the Library in Users/Shared report permissions issue on 10.6 and later, which may be related to changes in ACLs at that point. You might avoid these issues by putting the Library on an external disk set to ignore permissions.
I have been doing what JasonOnMac has been doing since Snow Leopard, AND I have the same issue. AND I used to resolve it the same way. Recently, iPhoto want to repair the permsiions on it's own (and it take a while), and now iPhoto wants to repair permissions OFTEN, not on demand after I found issues from a recent import from my wife.
I found an article on Aperture where this was caused by folder permissions.
Users/Shared me: Read & Write, staff: Read & Write, everyone: Read & Write
Users/Shared/Pictures me: Read & Write, staff: Read Only, everyone: no access
Users/Shared/Pictures/iPhoto Library me: Read & Write, staff: Read & Write, everyone: Read & Write
I am wondering if the Users/Shared/Pictures permissions should match the other two.
I am not a Unix expert, and am conservatice with changing file permssions unless I really understand what I am doing.
I suppose I could purchase a Firewire Drive and move the library to that as described in HT1198, but I have been doing this for 2 1/2 years without trouble until recently.
It may be too early to be confident, however I changed the permissions as follows: Note: the iPhoto Libray resides on iMac A.
iMac A: Users/Shared/Pictures me: Read & Write, staff: Read Only, everyone: no access
iMac A: Users/Shared/Pictures me: Read & Write, staff: Read & Write, everyone: Read & Write
I have successfully:
iMac A: Opened the iPhoto Library under my wife's account, then
iMac A: Opened the iPhoto Library under my account, then
iMac B: Opened the iPhoto Library under my account on another Mac on our network and made library modifications, then
iMac A: Opened the iPhoto Library under my wife's account.
In each case, iPhoto did not go into "examining the Library, nor did it need to repair permissions". The Library and iPhoto closed promptly without errors or inconsistencies.
I will keep my fingers crossed since it is hard to confidently trouble shoot without a higher level of understanding of Unix permissions and the details of the iPhoto Library.