One of the things I find amusing about the IT business is how often we create unintended consequences for ourselves.

Last week at work we ran into an interesting dilemma: We have a nice set-up to enable some level of single sign-on for our external users (business partners), across a suite of applications they use. We're preparing to deploy some browser-based COTS software into that suite of applications. Like most applications, the new one has a "log out" button.

When the user logs out, we'd like to take them back to a page that says, "You have logged out. To log on again click here." But we can't, because once they click on the log-out link, our "single sign-on" becomes "single sign-off". Before they can see any page on our partner network, we have to send them to our corporate log-in page.

We have options, so it's not like this is a huge problem. But no one thought of it before, so we're going through a bit of churn while people get their head around the problem and decide how they want to deal with it.

So don't forget, "single sign-on" also means "single sign-off".