Prepaid Softphones?

Just a little question... I have noticed a lot of buzz lately about internet softphones like Skype, Glophone, Dialpad etc... Is this just a fad or are these products really marketable as stand alone prepaid products?

I know they have a use for the online community kind of things like Google, Yahoo and Ebay who just want to be able to add voice commnunication to their text chat.