You can burn any format from iPhoto whatever it stores (or you save) and you can burn ether an "Event" or any chosen/made "Album" whatever format you have... when you click "Burn" it asks you to insert CD or DVD and it'll give you circle with green as available space and red if it too much, so you can see if you have enough or too much to put on DVD/CD... just try one you'll get the hang of it... and as for you direct question , I think it burns as individual "jpeg" pictures, other word you are not going to have an iPhoto display when looking from DVD... rather it's going to look like from "Finder" view...
Also you can select all the pictures/images that you want to burn and while they are highlighted press "Ctr-I" and it'll give you information on how many Megs/Gigs of pictures you have... on CD you can put about 700 MB and on DVD's about 4.7 GB ... I am against double sided DVD's 'cause I've read they do go bad faster...
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"Cherish forever what makes you unique, because you're really a yawn if it goes."
-Bette Midler-
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