The most famous writer to have moved from a blog to a book deal is Julie Powell, author the immensely popular Julie and Julia: 365 Days, 524 Recipes, 1 Tiny Apartment Kitchen: How One Girl Risked Her Marriage, Her Job, and Her Sanity to Master the Art of Living [B POW].
A recent entry into the blog to book genre is the Pioneer Woman, Ree Drummond, whose book is The Pioneer Woman Cooks: Recipes from an Accidental Country Girl [641.59766 DRU]. Ree fell in love with a rancher and moved away from her city home to become a modern-day pioneer woman. You can read her colorful postings at The Pioneer Woman.
Anyone can turn a blog into a book to share with friends/relatives by doing a Google search on "blog into books" and you will end up with dozen of places that will bind your blog postings into a book. Unfortunately, landing a publishing contract is not as easy or I would have done it a long time ago!