Paul has made a nice post on his blog about the use of the secure external password store and specifically he has compared the use of a Wallet to that of storing a password in a text file (such as a script) and what the benefit is in terms of using a wallet generated and managed by Oracle to that of simply using a file. The conclusion is that they are very similar because the weak point is file permissions. Paul has shown how you can use secure external password store and create a wallet on one machine and then copy the wallet to another and simply use it to connect to a remote database without knowledge of the password.
Paul's article is called "Oracle Wallet AUTO LOGIN ~ common misconception corrected
" - the common misconception is that the wallet is tied to the machine or user its create on/for - It is not!
Also for background reading Tim has an excellent paper on how to use Secure External password store here
Nice paper Paul!