Hi Klaus,
iMovie '11 also does pretty much as you've described for iMovie HD 6. The picture (or video) will always import in it's original form. So, for example, a portrait image will import just as it appears in iPhoto. Of course, it will have black on each side whether the video aspect is 16:9 or 4:3 (when the image is set to "Fit" in the Viewer options).
In the Viewer, iMovie '11 gives us a choice as to whether we want to "Allow Black" or "Disallow Black". In the latter case, if Crop is chosen, a green moveable border will be framed around a section of the image, in the same aspect ratio as the project. Likewise, if Ken Burns is selected, both a green and red border will appear, allowing the setting of the start and end sections respectively (including the size of these sections). The start and end positions can easily be reversed with one click on an icon.
Hope this clarifies things. I think Karsten was just indicating that to fit a whole image into the frame (such as a portrait image), without cropping or showing black, would require distorting the image to make it fit with all pixels intact. Hence his tongue in cheek remark about showing "eggheads". 🙂
Regards
John