concur_clover114 as of now all it means is that you will have to enable the ability to sideload/install unregistered apps through a cumbersome, but really just a minor inconvenient process, part of which is waiting 24 hours after enabling it. It's not the end of the world for end users or developers, and the enabling process is a one time thing only so once you do it, you can go on business as usual installing whatever you want.
What worries me is the trend Google is heading in. When this thing rolls out it'll be inconvenient, but more than that it's a declaration of intent. Maybe in a a few more years they'll decide to lock it down even more. But for now, it's nothing to worry about.
I hope that clears it up for you. If not, ask some more questions and I'll be happy to answer if I can.