My wife actually wants to get a Toyota Prius Hybrid. We drove both the 08 Civic Hybrid and the 08 Prius - we both prefered the Prius over the Civic. Better gas mileage, more room, nicer interior, and a better hybrid-parts warranty. We've decided to wait, though, and see what the 09 model offers - it should be a redesigned model year. Rumors are saying possibly 20% increase in mpg (Prius is rated @ 45-48 in 08 EPA estimates, and 51-60 in 07 and earlier EPA estimates), and maybe even a plug-in feature.
Right now she drives about 12,000 miles a year in a car that gets about 18mpg on average. Prius owners claim an average of around 51 mpg. She pays roughly $2,000 dollars a year in gas right now, based on $3/gallon gas prices. The Prius would save her roughly $1,300 dollar per year - basically replacing the battery pack cost in two years (Toyota warranties the battery packs for 8 years/100,000 miles - btw). I've really only read positive stuff about the Prius from it's owners. Other than it's exterior design (which I don't like), I'm confident it will be a good car for her.
You also don't have to go through emissions testing, and can also drive in HOV lanes in it.