TED Spread is the difference in prices in three-month futures contracts for U.S. Treasuries and three-month futures contracts for Eurodollars. The contract MUST have identical expiration months...very important.
The TED Spread is primarily used to measure credit risk. A decreasing TED spread indicates a decreasing default risk, and vice versa. This is a well known indicator, and can be found online or in any financial periodical.
This 6 month chart of the TED spread should give you an idea of how it moves:
Related terms: LIBOR OIS Spread, VIX, VIX Options