The reactor and building were initially enclosed in a Sarcophagas to prevent further spread of radioactive material over the years, after the initial smothering in material dropped from helicopters. It was only intended as a temporary measure. A building designed to last 100 years will be built with international funding and participation; scheduled to be done by 2008.
An area of 30km size around the plant is still quarantined, but outside of that the area initially evacuated has radioactivity levels that have decreased to safe values through natural processes. Certain types of food grown in areas that were contaminated are still monitored and restricted from sale in other areas.
The restoration of the area around the plants will go on for many years. Eventually the reactor and building will be removed and disposed of in a geologically safe area.
National Geographic magazine has done several articles, with pictures, over the years. Search their website for Chernobyl. The April 2006 issue has an article with a good drawing of the new shelter.
See the IAEA web site for more detail:
Last updated June 27, 2012, 8:50am CDT.