Great post; I knew about this for several months now since Solaris announced it, and they even kept their word about the date of the free release. However I did not like the book when I've tried it a while ago in its print version, so I forgot to post about it here.
Solaris has many other free goodies, including the book published in serial installments by C. Roberson
Check:
http://www.solarisbooks.com/