iPhoto 7 and Aperture work really well together. In iPhoto you can drag in any image from your Aperture library using the Show Aperture Library feature in the File menu. You can also add images directly from Aperture simply by dragging and dropping from Aperture to iPhoto.
However, when you add images to iPhoto, by default iPhoto copies them to your iPhoto library as a new file. This means that you now have two copies of the file living on your hard drive. To get around this simply open your iPhoto Preferences and under the Advanced tab uncheck the Copy items to the iPhoto Library.
Now, whenever you drag images from Aperture to iPhoto, iPhoto will treat the files as referenced masters. In fact, in iPhoto you can Ctrl-click the image and select Show File. A Finder window will pop up and if you had added that image from your Aperture, you will see that the Finder has pointed to the Preview image file within your Aperture library package.
What is really nice about this feature (other than the fact that it saves some hard disk space) is that if you make a change to an image in Aperture, you will see those changes in iPhoto. This holds true of course until you make changes to the image within iPhoto. If you edit the image in iPhoto, a new file will be created within your iPhoto library to reflect the changes. You can always revert back to the original in iPhoto, and if you Ctrl-click the file, you will now see the option to Show File, or Show Original File.
In order for all of this to work, you will need to be sure to set up Aperture’s Preferences to Share Previews With iLife and iWork. You will also need to be sure that Preview files for the images you are interested in have had a chance to generate after importing into Aperture. You can check on this using Aperture’s Show Task List feature found under the Window menu.
This type of seamless integration between Aperture and iPhoto 7 offers some really cool and fun tools. As Derrick mentioned in a previous post, you can sort of think of iPhoto 7 as a giant plugin for Aperture.