Why does Android prompt me with "Enter the credential storage password" when I attempt to connect to a secured WiFi network? When I connect my iPhone to a secured WiFi network (at work), I'm prompted for my Username and Password. (And then I'm prompted to accept what I presume is an SSL certificate.)

But when I select the same network on my Motorola Droid or HTC EVO 4G, I'm prompted with "Enter the credential storage password".  What is this password?
I went into Settings -> Location &amp; Security (on Droid, Security on the EVO) -> Use secure credentials, and entered the credential storage password.  Then I was no longer prompted for this password when selecting the WiFi network.