LIBOR is the London Interbank Offered Rate. It is a daily reference rate based on the interest rates banks in the London wholesale money market (or interbank market) offer to lend unsecured funds to each other. LIBOR is usually slightly higher than the London Interbank Bid Rate (LIBID). LIBID is the rate the same banks are prepared to accept deposits.
With the 1 year LIBOR Rate currently at 2.77%, there is not a big hurry to refinance "reasonable" ARMS now.
Web Page of "Current Libor Rates"
Make sure you read our survey of the best mortage rates.