My wife and I are a same-sex couple, and had a very difficult time finding a baby book for our soon-to-be-born child. As other posters have mentioned, it's hard to find a baby book that doesn't talk about "mom and dad". We'd be happy with one that talks about the "parents" or "mom and mom", but were surprised by the lack of options.
I spent a long time researching our options, so thought I'd post what I've found in case other people are looking for the same thing, or have better/different ideas. I included the prices I've found, but those obviously may change.
And Then There Was Me: $30 on Amazon. Some people say the construction is flimsy, others think it's nice.
http://www.amazon.com/And-Then-There-Was-Me/dp/1930218036
Welcome to the World Baby Memory Book: $30 on Amazon. Produced by National Geographic, seems to be mostly pictures of animals, but seems inclusive ("parents" rather than "mom/dad").
http://www.amazon.com/Welcome-World-Keepsake-Baby-Book/dp/142621314X/
Hallmark: $40 plus shipping. Add-ons for same-sex parents included (you just switch out the pages you don't want and add what you do want).
http://shop.hallmark.com/baby/baby-gifts/retro-alphabet-5-year-memory-book-1BBA7019.html#q=baby+memory+book&start=1
Our World Our Families: $40 and free shipping.
http://www.ourworldourfamily.com/samplepages.htm
Love Leaf Books: About $46 plus shipping.
https://www.etsy.com/shop/LoveLeafBooks
Baby Steps: About $50
http://www.babystepsbook.com/same-sex-baby-book/
Tessera Memory Book: About $80, with add-ons for same sex parents.
http://www.tesserapublishing.com/uploads/Baby%20Book_SAMPLE%202012.pdf
Rag and Bone Bindery: About $80 plus shipping. If you go to their Etsy site you can usually find a coupon to reduce this to about $60 plus shipping.
http://www.ragandbonebindery.com/babybook.aspx
Babysakes: They're a keepsake store rather than an individual printing company, but have a good selection of baby books for non-traditional families.
http://www.babysakes.com/Gay-and-Alternative-Baby-Books-s/46.htm
The Story of Me: Seems like it's no longer available; company seems defunct.