Well it does really.
You say you have multiple folders of images and iPhoto won't let you import them as such.
Well, let's say one of those folders is named;
"Holiday In France". If that folder is on your Hard Drive you can drag'n'drop it directly into iPhoto's Source Pane (found to the left of the main window) and it will be imported as a group. It will be displayed as an 'Album' in the Source Pane, so if you click on the album icon the contents will be shown in the main window to the right.
iPhoto will add the images to the central Library as well, but the sorting will have already been done by this method of importation.
So if you have multiple folders on your HD (
I'm not sure if you can drag'n'drop from a DVD directly into iPhoto, by all means give it a go first.) then just drag'n'drop them one by one or a few at a time or even a batch at a time, depending on how you want to do it. Obviously the more you add at any one time will chew up processing time so it's up to you.
This is a very easy way to achieve a sorted iPhoto Library from scratch when you're talking about importing a gazillion or so images.
Here's a quick visual guide
-