How is this compared with XBL or Steam? Please, fix if it's wrong:
Steam only allow 1 active account. You can have offline mode, I suppose that with PS3 will happen the same, if you deactivate a console, but that console is not online, no problem.
XBL only allow 1 active account (but you can have it in 2 because a game is playable in the console that you downloaded the game and also in another one console with your gamertag if you are online). You can change the "active console" once each year.
We still have to see how the activation-deactivation works. If it's without limit of times, it's no problem for any regular PS3 user, even if he has several PS3 in different houses (or even in the same house). Assuming that the 3, 4 or 5 PS3 won't be active and online at the same time, you could deactivate a console and activate the one that you want to use with the same web browser of the console. People won't be using everyday different consoles to play games (also, yo can keep always active the one that you use more to play, to prevent losing time each time that you want to play).