The primary heating fuel in Maine is oil. Although transportation is the by far the largest percentage of oil Americans use, it just doesn't make sense to continue to support foreign oil when we do have alternative solutions available. Throughout many communities in the northeast natural gas infrastructure is being expanded and installed, allowing delivery of a cheaper and cleaner fuel to heat our homes. With the current oil and natural gas prices, even just converting your boiler or furnaces burner will save you on annual heating costs (~25-30%). If you decide to replace your entire heating system and upgrade to a high efficiency model, you'll be able to reap extensive monetary savings AND improved energy efficiency.
A recent TED talk given by T. Boone Pickens addresses many of these Oil vs. Natural Gas issues. Worth a watch.