At this years Debconf15, a nice overview of the Let’s Encrypt project was given that you can view here. It’s a nice exposition as to the current broken state of CA’s and the projects plan to solve them. Let’s Encrypt is going to be making free certificates available in the next month or so.
Will this be a game changer for commercial CA’s that make their profit off of selling certificates? Probably not in the short term and a large part of the answer will depend upon adoption and getting the Root & Issuing CA’s added to the trusted browser stores.