Advertisers can still target their ads to an entire site, but they can now also target your individual ad units or groups of pages based on how you've set up ad placements using custom channels.
The second change is that advertisers can bid on placement-targeted ads (formerly known as site-targeted ads) on a cost-per-click (CPC) basis. Previously, advertisers could only bid on these targeted ads on a cost-per-impression (CPM) basis. Just as with contextually targeted CPC ads, you'll generate earnings for valid clicks on placement-targeted CPC ads.
While you can also add the URLs of specific CPC placement-targeted ads to your filter list, please keep in mind that all placement-targeted ads will participate in the ad auction with contextually targeted ads. Allowing more ads into the auction will help increase competition and ultimately your revenue.