This book is definitely on my to-read list. Margaret Fuller's relationship with Adam Mickiewicz was recently explored in a Lithuanian play, Mistras, my wife and I saw. She was portrayed with a blonde bouffant and all the verve you would expect from a woman who touched many persons' lives in her tumultuous 40 years. The play included her as part of the entourage (also included Frederic Chopin and George Sand) that surrounded the famous poet in 1840's Paris as he lamented the sad state of affairs in his homeland, hoping to rally Polish-Lithuanians as part of an army to reclaim their land lost to the Russians.
Megan Marshall's new book has been very well received and appears to help fill in the holes in the era we are discussing in relation to Hawthorne's The Blithedale Romance.