PANIC!!
I called the app tech dept and used joachims case no. as a reference. no matter how many times i referred to his case, the different people on the phone didnt seem paying attention, and kept doing their normal trouble shooting, and pretending this could only be a stand alone problem with my hard drive - and not the case of a faulty new update from apple.
first we tried pressing the command+option key while launching iphoto, and then choose repair - but the update got stuck again on step 5, 99%..
then he had me go in to the iphoto library and remove the master file to the desktop before relaunching iphoto. now i got a completely clean new iphoto 9.3, and then dragged the master file folder into iphoto again to import the complete library again.
2 hrs later, after importing approx 22.500 photos I now have all my photos back, but all my endless weeks of creating folders, tagging names, places, creating meta data, and doing beautiful photobooks, ALL of this is now lost...
Hopefully I can re-create all my work from my time machine back-up. I think so, but I'm crossing my fingers.. Otherwise I will call the the App Tech Dept later today.
But how on earth can Apple create this problem and then now informing their helpdesk supporters?! I had to repeat at least 10 times that this wasn't just my computer behaving this way - this was a bug coming from Apple's new update...but they didn't seem to listen.
Good Luck!