Q: Aperture 3.4.3 - shared photo stream option missing

This is what the Photo Stream preference looks like in my 3.4.3 version of Aperture:

And this is the System Preference for iCloud

What do your screens look like?

Where do you see "Shared Photo Stream" under "Recent"?

The Photo Streams are supposed to appear in the "Web" section of the library, not in the "Recent" section. Are you seeing a recent project there, accidentally named "Shared Photo Stream"? Then you are dragging your images to a project, and not to a stream.

Look in the "Web" section of the Library inspector for "Photo Stream". If the stream is hidden, hover with the mouse to the far right of the title "WEB", until the word "Show" appears.

Selecting a stream and opening should make the "PhotoStream" button appear in the footer of the window.

Regards

Léonie

Shared Photo Stream requires 10.8.2 to use per http://support.apple.com/kb/TS4379

Good catch. That would definitely explain it!