UPDATE

Had a "duh!" moment today. I was in the Aperture preferences for another reason, and I realized I'd missed the location checkbox in the Export preferences:

Sure enough, deselecting "Include location info in exported photos" does just what you'd think it would. I tested it with an export to Picasa and worked perfectly. No more ugly workaround. I'm keeping the rest of the original post below for posterity (and to remind me to be a better detective in the future :)

I've enjoyed looking at maps since I can remember. And naturally, I really like the Places feature of Aperture 3 (and it's really fun on a iPad, I must admit). So I tag all of my photos with location data. And I like including this data in most of the images I post to Google+. But there are occasions where I don't want to divulge where a photo was taken. Photo I took from last summer's visit to the Loire Valley, yes. The one I took in my back yard, not so much.

In Aperture 3's advanced preferences, there's a check box for including location data in published photos:

An option I was very happy to find. And for my first export to Picasa directly from Aperture, I first disabled the location information via the Preferences, did my export, then re-enabled. But, I kept finding that the location data was still in my Google+ photos. And I didn't want to turn off all of the EXIF data. I like to maintain at least a copyright tag in the image. Also, when I look at other people's photos, sometimes I want to see what their camera settings were...so I want to preserve that for anyone viewing my photos.

After much trial and error, I've come to the conclusion there's a distinction in Aperture between publishing an image and exporting an image. Note that the preferences option specifically says "location information for published photos". In Aperture-speak, this means sharing online via the MobileMe, Facebook, and Flickr integration. This preference does nothing when exporting images. [Note that I'm making an education assumption here based on what's in the Sharing Your Images Online section of the Aperture 3 User Manual. I don't use any of these services and didn't do specific testing.]

So, where does that leave me? With an ungraceful workaround - but one that works nevertheless. When I have a photo I want to export to Google+ without location information, it becomes a three step process:

1. Select the photos for export and do Metadata -> Remove Locations
2. Export the photos
3. Do Edit -> Undo

Yup...this is a hack, and I hope the day never comes where I forget that Undo step.