With the November firmware update, Sony cut down the number of PS3 activations from 5 to 2 per PSN account. For someone like me, this doesn't seem to be that big of a deal because we only have one and I doubt we'll get a second. But it is apparently a big deal for a group of people on Change.org as they have submitted a petition to revert the number back to 5.
I'm guessing this is partly due to sharing a PSN account with friends or just owning a large number of PS3s, as this quote from the petition suggests: "This has effectively turned many PS3 consoles into very expensive paperweights!"
I also wonder if it has to do with people forgetting to deactivate their old PS3s when they get a new one. They ditch their old PS3, pick up a Slim, and then get smacked with, "Oh noes! You've maxed out your PS3 limit on this account!"
If you fall into either camp or just like having the possibility of having 5 PS3s on one account, then stop over at Change.org and sign the petition. As of writing this news post, there are 26 signatures.
However, everyone should be advised that the likelihood of Sony caring about this petition is fairly nil. They chose to limit the number to prevent piracy with sharing PSN accounts, and as we all know, Sony has had a few problems with piracy as of late, making it doubtful that they will risk losing money on the possibility of shared/pirated games once again.