The CFTC is the federal agency (of the U.S. Federal Government) charged with enforcing federal regulations governing the sale of commodity futures and options. Effectively, this group does for pork bellies what the Securities and Exchange Commission does for your formerly overpriced Yahoo stock - it investigates fraud and other unfair trade practices, then it prosecutes criminal and civil enforcement proceedings against the perpetrators.
Most of the CFTC's work involves futures contracts. These contracts are agreements to buy or sell specific commodities at a set price at some future point in time. Futures contracts originally evolved as a way for farmers to protect themselves against the vagaries of the marketplace - they could "lock in" prices for specific crops well in advance of the actual harvest. Through proper management of futures contracts, a farmer could guarantee a stable income over the years, regardless of the relative abundance of any particular crop or product.
Many other commodities are also subject to futures contracts - gold, silver, oil - just about anything that can be produced by an agricultural or industrial society. Because futures contracts are so widespread, they are traded on exchanges much like stock exchanges. This is where the CFTC comes into play.
The Commission regulates the futures market in two main ways. First, they directly monitor the markets themselves, to ensure that all market participants comply with federal regulations. They also monitor off-market trading of commodity futures, a task which has become much more important in the age of the Internet. It is much easier nowadays to bypass the market and directly contact potential futures traders, but it is also much easier for scam artists to directly contact marks and promote fraudulent futures schemes. The CFTC plays an important role in preventing such schemes.
Second, the Commission also oversees the professionals who are licensed to trade in futures contracts. Much like the SEC oversees licensed stock brokers, the CFTC ensures that licensed traders follow all the necessary regulations and begins enforcement proceedings against those who don't.
To this day, no one has successfully explained to me why anyone would want to buy a pork belly, either now or in the future.
Source: http://www.cftc.gov/cftc/cftcglan.htm