Source: http://www.siliconera.com/2011/11/04/on-november-18-psn-games-can-only-be-activated-on-two-systems/

Sony Computer Entertainment is changing their digital game activation policy. Currently, games purchased over PlayStation Networkcan be activated on five different devices. Some publishers like Capcom created a work around to restrict games to one console, but titles like Final Fight: Double Impact are far and few between.

Today, SCEJ announced games purchased from PSN on or after November 18 can only be activated on two devices. Games purchased earlier will not be affected and can still be activated on say five different PS3s. This policy change spans all of Sony’s gaming devices – PlayStation 3, PSP (all models including PSPgo), andPlayStation Vita.

After the change is made users who want to install a game on a third device will have to deactivate it. Sony will make this process easier by allowing remote deactivations via a PlayStation Network account management website instead of having to deactivate the game from a console.

Sony’s reason for the policy change is to balance content creator rights and customer convenience.

Well...I never understood why they allowed sharing in the first place considering they lose sales that way so I never complained when it was 5 and now it's 2...I can't complain either as I only share with 1 other person so...

"Sony will make this process easier by allowing remote deactivations via a PlayStation Network account management website instead of having to deactivate the game from a console."

Thank God!!
This has been a pain in the ass.

Although I currently have 2 ps3's both of which I use and log into on a regular basis. If I get a vita, does this mean I will have to deactivate one of them?

That is really sad for Sony PSN users....bad move sony

Of course, this will suck for gamers. I've given away so many free PSP games to so many people, it's ridiculous! But it is what's best for Sony. I wondered what was going through their heads when they allowed so many different consoles access to their software--especially now that there are full retail games available for download on the PSN.

Making money today means Sony will be alive tomorrow. Good move for them. Long overdue. Now I can stop supplying games to my freeloading friends!

Well they should of done this from the start to prevent possible losses.