They won’t secure Georgia, but simply the areas around the disputed regions. It will probably be an initial NATO or EUFOR but will probably end up under the U.N. The U.N. currently have a buffer zone/region in Abkhazia. All they will be doing is keeping the peace between Georgians and Russian forces. Think of it as like the Green line that is currently in Cyprus except on two fronts.
CNN reporting that Russian planes are still bombing.
It's similar to the way the U.S. maintains bases and forces in other countries, as a springboard for possible action. We do not control or occupy Korea, Japan, Germany, etc. but we do not want them in hostile hands.
As for U.N. peacekeeping forces, they are a joke, as Rwanda and Lebanon show.