Just a quick update to let you know that Black Tree is now available as an eBook. I know a lot of people have been interested in the digital edition.
It will be available soon across the usual eBook platforms: Amazon Kindle, Barnes & Noble nook, Apple iBooks, etc. I'll let you know when that's the case (it can take a couple of weeks but will likely be much sooner). However, you can buy the eBook right now from Lulu. Enjoy.
Update: the eBook is also on Apple iBooks now.