With the new PlayStation game sharing restrictions set in place today, you might have to might have to activate or deactivate one or more of your PS3 or PSP systems to make sure your games are playable on the right systems. With purchases limited to only two PlayStation devices, you might have to do some juggling. As someone that heads up a major videogame website, I know that I'm not a typical case, but I have 3 PS3s and 5 PSPs, and I use them all for various purposes. You can imagine how happy I am about this change.
Management of your devices is easy through Sony's website. You just need to log in and work with systems you'd like to deactivate.
Beyond this, another deactivation feature might prove useful to those that, like me, have a whole bunch of systems, and might not have access to them all at this one time. For example, one of my PSP systems is about 5 hours away from me right now. A full remote deactivation of all PlayStation systems is possible. The account management application says that this is only possible every six months, and that you'll have to activate each system again through the XMB. If you're dealing with a lot of of systems, this clean wipe may be the way to go. You'll find this option under the Account tab.