Is there an iPhone 4 car kit for charging, music, and hands-free calls?
If you already happy with your connection and the only main problem is the Not Charging part, I would strongly suggest that you contact the creators of your connector and ask for an upgrade as it is a simple power problem as the new iPhone 4 needs different Amps to charge correctly.

If you want a new connection, I know Dension is very good on this and integrates well with several brands of vehicles so you can use your radio to also see music details.