Very cute idea ... My brother and sister-in-law have done something similar with their two girls, but opted to take the group photo each Mother's (with an heirloom quilt as a backdrop) and Father's Day (with their backyard hammock as the backdrop). It's fabulous to see the array of changes that have taken place over the years AND they've all got an amazing keepsake. Priceless!
Awwwwww, so sweet! This could be a great way to take pictures on a regular basis to show growth. Plus, a chalkboard wall would be super fun to have in the nursery, both as a changeable piece of artwork and also for when Baby W grows up a little.