I was looking at "Version Control with Git, 2nd Ed." which is due out in July. There's a button to push to preorder the print edition. I'd like another button allowing me to either preorder the ebook, or to be notified when an ebook (early release or complete) is available. I would certainly use such a button frequently.
Thanks for taking the time to write us with this idea! We've recently been discussing adding more options for ebooks, like pre-order, so your feedback is really helpful. I'll pass your comments on to the group, and I hope that we'll be able to do something like this soon.