Very interesting, daffy4u! It must be recent. I wonder if it was implemented along with the ebook gifting changes? However, I see something different than you.

I am logged into my Amazon account, and I do have the Kindle desktop software installed (Mac version). Instead of "Read it now on PC", my computer says "Kindle Edition: Read First Chapter FREE". When I click the button, I thought it might prompt me to download a sample. Instead it brings up something called "Kindle for the Web Beta" which is a book previewer similar to the "Look Inside" p-book viewer. Within the Kindle for the Web previewer is a link to the Kindle Store and also a button to purchase the Kindle ebook now.