Well, I'd do some math quick to figure out your Total Cost of Ownership...
Hybrid Car that gets 60 mpg
Regular car that gets 25 MPG
Fuel costs: $2 / gallon
Total Miles / year 20,000
Car A costs:
20,000 miles / 60 mpg = 333 1/3 gallons / year
333 1/3 gallons x $2 / gallon = $666 2/3 / year in fuel.
Car B costs:
20,000 miles / 25 mpg = 800 gallons / year
800 gallons x $2 / gallon = $1,600 / year in fuel
TOTAL SAVINGS PER YEAR: $1,600 - $666 = $934
So, if you plan on having the car for more than 5 years it's worth it.
But don't forget that 1) gas prices will probably go up again which will increase the savings and 2) there are tax rebates (at least in the US) for hybrids.