You can do multiple wallets by just creating multiple accounts and tuning bitcoin client on each one separately either by runas on windows or su on linux.
This is true but it has a few problems: It is a relatively complicated process, two clients running at the same time needs additional adjustment of port numbers, the new client will start downloading all blocks starting from zero which will take ~12 hours until completed, the newly created wallet file must be found in the nhew profile's %appdata% folder unless maybe even some more command line switches are applied (and also the running client won't show any hint about *which* wallet file it is currently operating on), then after moving the newly created wallet to its intended destination (encrypted backup or usb drive) the profile folder has to be securely wiped and the user deleted again. All this for just "exporting" some money into a new wallet.
I think some clear and easy UI for easily handling (moving, creating, splitting, merging, switching, key-changing) of the only and most important data file of the application, the wallet file, would be very helpful. The user should at any time have full control (including full path in the title bar) about which wallet is currently opened and standard actions known from other applications like open, close, new, import, export, etc. should be provided.
Combine this with mandatory encryption of private keys in the wallet (ask for passphrase before transaction) and a lot of problems and a lot of questions of confused users will go away.