The article 'Which hybrids save you money?" in the October 2008 Consumer Reports compared hybrids with similar all-gas models to see how the each car's 5 year total owner cost compared.
The Toyota Prius was a clear winner with the lowest total 5 year owner cost ($28,250) whereas the Lexus G5 450h Hybrid had the highest (70,250). So just picking a hybrid does not necessarily save money or the environment, but taking the total vehicle into account, can do both.
The Prius is a very nice family sedan with lots of features so it was great to confirm my earlier post that it is very economical as well (just as we would expect) -- useful features at a low total cost.