multi wallet idea is NOT supernet. supernet has you connect to a server with wallets in it. all you download to use it is a website link to get onto thier server, your wallets are NOT locally stored and because of this i feel heavily that it is not a safe system.
as goldmaxx said my dev group is working on a multiple coin wallet. so far we can run 2 coins at the same time and it works (so essentially the multiplecoin wallet is done) but there is no gui interface for your average user so we are building that now, only option atm is use the command line like a daemon