I know the ERC223 specification has been out there for at least a few months now, and it does offer advantages over ERC20.

I am unsure if it's supported in current wallets. I know it's backwards-compatible with respect to the methods it implements (ERC223 is a superset of ERC20), however I haven't looked into it enough to know if there is anything needed for wallet/client implementation.

It's most certainly the way that Ethereum tokens are going to go at, least it's v.next.

Best regards,
Ben