Nicolle is totally on when it comes to Emma's style. She has helped me find both of these sweaters:
From Preggers:

Anthropologie Moth Leaf Petals Snap-Up Cardigan
From Mash-Up:

Milly Cashmere Cardigan
Nicolle also let me know that Milly makes the spring green sweater with the off-white buttons and collar from Showmance. (I suspect they might also make the periwinkle and cream sweater from the same episode, but I'm not positive.)
Another reader wrote to say that the Moth petals sweater is for sale on eBay right now (there are three of them! - two mediums and one small), and in my search for the Moth sweater, I found the blue Milly (size large) as well. A quick search for "Anthropologie Moth petals" and "Milly blue cardigan" will turn them up easily if you're interested!
Thanks again, Nicolle and everyone!