Yes, I know they have charged for years: I have read on other forums, various "guesses"; this is one of the little annoyances of sprint, if I were trying to decide between one carrier or the other.

I have had other carriers, who don't charge to forward, except the minutes used. Also the old bell south dcs( and I believe cingular currently) has what was called 2 in 1 forwarding in which calls would the sent to the handset, and another phone simultaneously; this was handy at the time and there was no charge for the forwarded call at all.