I'm a writer/illustrator working on a picture book. I paint digitally and it would be much easier for me to present the book digitally, say on DVD. Is that an acceptable format?
Yes, but you should also submit high-res printouts of the manuscript - most publishing companies or agents will not want to print out colour copies of your digital files ... If in doubt, check the relevant submission guidelines or call/email to find out if you can submit that way.