Sorry, but I can't see a way to request a feature, so I'm logging an issue.
To quote from a thread of someone reformatting their hard disk and thinking that they had a back up of the wallet.dat when they in fact actually backed up the program files.. http://forum.bitcoin.org/index.php?topic=24923.msg310702#msg310702
Maybe add a backup option in the client. You click on backup and it prompts you with which drive do you want to save the wallet.dat as wallet-yyyymmddhhmmss.dat ? With big red warnings that the backup file is not encrypted, the same care must be taken with it as with a real life wallet full of cash. And that if you have no backups and your hard drive dies, you have lost your wallet, with little chance of recovering it.
Instead of people magically knowing where to go to find their current wallet.dat file. Windows: C:\Documents and Settings\username\Application Data\Bitcoin (AKA) %APPDATA%\Bitcoin Mac : ~/Library/Application Support/Bitcoin Unix : ~/.bitcoin
Bert