I just tried to download it fro this URL:
and I received this message: "The version of iPhoto installed on this Mac must be updated through the Mac App Store. Check the Mac App Store to see if an update is available."
I therefore can't download the update from the App Store or from the Apple Support site.
Apple support suggested the following (which didn't work for me, but I'm sharing as they might work for others - I'll keep the post updated when I hear back, again):
1) Double-click the App Store icon in the dock.
2) Enter your Apple ID and password.
3) Click Purchases.
4) If you haven't previously accepted your bundled iLife applications within the Mac App Store, you should see your iLife applications appear in the Accept portion of the screen. Click Accept.
You may be asked for your Apple ID and password once again. Your iLife applications now move to the Purchased section. These applications are part of the software that came with your Lion based computer. Your account will not be charged for them.
5) Click Install to compete installation of your applications.
If this does not work, follow the instructions below and then repeat the steps above to accept the iLife apps again.
1) Close the Mac App Store.
2) In Finder, click on the Go menu.
2) Click Go to Folder.
3) Enter ~/Library/Caches/com.apple.appstore/
4) Drag adoption.plist to the Trash.
5) Relaunch the Mac App Store.
You should then be prompted to accept the apps for your current account.
If you are not prompted to accept the apps when you sign back in to the Mac App store and click on purchases, please contact us back.